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Mechanical Seals
 

Mechanical Seals

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Mechanical Seals

Mechanical Seals

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    Mechanical Seals Mechanical Seals Document Transcript

    • GBH Enterprises, Ltd. Engineering Design Guide: GBHE-EDG-MAC-5702 Mechanical Seals Information contained in this publication or as otherwise supplied to Users is believed to be accurate and correct at time of going to press, and is given in good faith, but it is for the User to satisfy itself of the suitability of the information for its own particular purpose. GBHE gives no warranty as to the fitness of this information for any particular purpose and any implied warranty or condition (statutory or otherwise) is excluded except to the extent that exclusion is prevented by law. GBHE accepts no liability resulting from reliance on this information. Freedom under Patent, Copyright and Designs cannot be assumed. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • Engineering Design Guide: CONTENTS Mechanical Seals SECTION 0 SCOPE 0 1 INTRODUCTION 1 2 ADVANTAGES 2 3 DISADVANTAGES 3 4 BASIC PRINCIPLES 4 5 BALANCE 5 6 LUBRICATION 6 7 MATERIALS 7 7.1 Seal Faces 7.2 Secondary Seal 8 HEAT REMOVAL 8 9 DOUBLE MECHANICAL SEALS 9 9.1 THE 'TANDEM' DOUBLE SEAL ARRANGEMENT 9.2 THE 'BACK TO BACK' DOUBLE SEAL ARRANGEMENT Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • 10 EXTERNAL QUENCH FACILITIES 10 11 APPLICATIONS NOT SUITABLE FOR MECHANICAL SEAL 11 11.1 11.2 12 13 Emergency Duties - Fire Pumps Etc. Boiler Feed Pumps Incorporating a Balance Valve RULES FOR THE APPLICATION OF MECHANICAL SEALS 12 DEALING WITH SEAL FAILURES 13 SELECTED BIBLIOGRAPHY APPENDIX A - MECHANICAL SEAL BALANCE APPENDIX B - USE OF TANDEM SEALS ON LPG OR OTHER HAZARDOUS FLUIDS Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • 0 SCOPE This Engineering Design Guide presents the basic principles associated with the use of mechanical seals for the benefit of those involved in the design, selection and operation of pumps and agitators. It does not attempt to advise on the particular make or type of seal for any particular application. For this latter purpose reference shall be made to the manufacturer's catalogues and difficult applications should be discussed both with the pump vendor and the seal maker. 1 INTRODUCTION A mechanical seal is a device with which a seal is affected on a rotating shaft by close contact between two rigid faces normal to the axis of rotation. Mechanical seals are precision engineering components and care has to be taken in selection, in the design of the mounting arrangements - including provision for cooling, and fitting if the design aims are to be realized. In general pump manufacturers have only limited operating experience with mechanical seals and their seal selection is usually based on seal catalogues, frequently without discussion of the application with the seal manufacturer. If the application is discussed with seal manufacturer, the latter's advice is normally accepted without criticism. Seals are easily damaged by dry-running or by the ingress of abrasive solid particles. The latter is a particular hazard during the commissioning of new plant and special precautions may have to be taken at this time to prevent premature failures. This note is based on operating experience with mechanical seals in chemical plants. It is intended to give guidance on the integration of seals into the system to ensure maximum reliability. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • 2 ADVANTAGES The advantages of mechanical seals over packed glands are: (a) Reduced maintenance costs - but only if a life of some months operation is achieved. (b) Reduced leakage when in good condition - hence plant areas containing pumps handling flammable liquids can generally be classed as Zone 2 hazardous areas and not Zone 1 hazardous areas. (c) They require less space - hence the pump design can be more compact with less shaft overhang etc. (It is unfortunately true that few pump manufacturers take advantage of this since many pumps are still designed around packed glands). 3 DISADVANTAGES The disadvantages of mechanical seals compared with packed glands are: (a) More expensive - both in first cost and in replacement parts. (b) Require a higher standard of fitting. (c) Will tolerate less "run-out" of the shaft – especially axially. (d) Provide no support or "steadying" to the shaft. (e) CAN fail rapidly necessitating the immediate shutting down of the pump (although this is the exception rather than the rule) Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • 4 BASIC PRINCIPLES In the soft-packed gland, sealing is obtained by pressing a flexible 'packing' against the periphery of the rotating shaft. In the mechanical seal, sealing is transferred to a contact between a stationary face (the seat) and a rotating face attached to the shaft (the seal face). One of the faces is allowed limited axial movement to accommodate wear and is pressed against the seat by light spring loading (normally 1.4-2 bar) and the pressure of the sealed fluid. Lubrication is necessary between the seat and seal face to prevent rapid wear during rotation. Seal design is a compromise between providing adequate lubrication and avoiding the formation of an excessive lubricant film that would allow a high leakage path. Mechanical seals thus bear a close resemblance to thrust bearings, though in most practical seal applications lubrication tends to be in the mixed lubrication regime rather than the full fluid regime that is the aim in thrust bearing design. This means that, even with correct operation, wear of the faces will occur and the seal will have a limited life though this can be many years under favorable conditions. Moreover, the sealed fluid that acts as the lubricant will often have poor lubricating properties so that the seal face materials have to be selected so that they will operate under these conditions of lubrication without excessive wear. The lubrication regime is determined by the speed, viscosity of the sealed fluid, and the interface pressure. The pressure on the seal faces has thus to be controlled within fairly narrow limits for satisfactory operation. With sealing liquids at a pressure of above about 10 bar it is necessary to 'balance' the seal to reduce the hydrostatic pressure component on the seal faces. There are two limits to operation; a low speed limit below which a proper lubricating film is not developed and a high speed limit when the heat generated by viscous shear is sufficient to destroy the lubricating film. These speed limits cannot be accurately defined in terms of the operating parameters. In general, the lower limit is not of concern in centrifugal pump applications; however it can apply to autoclave agitators and similar applications. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • 5 BALANCE The principle of balancing is explained in Appendix A for the normal type of seal (e.g. a Crane 109). For other types, such as external seals, bellows seals or seals where the floating element of the seal is stationary the principle is similar. In all cases consider the various forces acting on the floating element of the seal. The balance factor defines the extent to which the pressure difference across the seal affects the mean pressure between the seal faces. In the simple unbalanced seal because of the need to allow clearance between the shaft and the seal faces, the balance factor is normally about 1.1 - hence a 1 bar increase in pressure difference results in an 1.1 bar increase in mean seal face pressure. If the seal is over-balanced there is a tendency for the high pressure fluid to get between the faces and 'blow' them apart. For this reason in practice, balance factors less than about 0.6 are not used. Normal value 0.75. 6 LUBRICATION For satisfactory operation it is necessary for a lubricating film to be established between the sealing faces. The mechanism by which this film is generated has not been completely resolved, though most recent evidence, see Bibliography Ref (6), suggests that with aqueous fluids it results from microwaviness of one of the seal faces (the soft face when one is used). This can result from the lapping process in manufacture but normally is formed during initial running. The microwaviness is generally a 2- period sinusoidal, but there is also some evidence for 3- period waviness, possibly resulting from relief of stress in a hard face that has been machined using a three jaw chuck. No attempt is made by the seal manufacturers to produce a surface profile of this type, their aim being to manufacture faces with a high degree of flatness and surface finish. This could be an explanation for some of the failures that occur when starting a new seal, breakdown occurring before the required profile is developed by running in. In practice film thicknesses lie in the range 0.25 to 2~m and the waviness height is about half this. It is clear from these dimensions that the mechanical seal is a precision engineering component and has to be treated as such for satisfactory Performance. Normal practice is to arrange for the higher pressure on the outer periphery of the seal; in this way centrifugal force tends to act against the leakage flow. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • For the majority of applications it is necessary for the fluid film to be substantially in the liquid phase. Therefore it is essential that the seal should be surrounded by liquid and this liquid must be sufficiently removed from its boiling point that it will not vaporize immediately on entering between the seal faces. Whilst in most cases the fluid entering between the faces at the outer edge must be liquid, the fluid leaving the seal at the inner edge is often vapor. The actual position on the faces at which the phase transition takes place or the manner in which it takes place is not known. However, attempts to run NORMAL types of seal deliberately on vapor have generally failed. 7 MATERIALS 7.1 Seal Faces It is normal to have one of the sealing faces of a low friction material that can tolerate a certain amount of dry rubbing (e.g. carbon-graphite, filled ptfe) to minimize wear and heating in the event of intermittent face contact. It is important for film formation that the faces should be readily wetted by the sealed liquid. This is a function of the wettability of the face materials and the surface tension of the liquid. Wettability characteristics:GOOD Cast Iron Ni-resist cast iron Fused Alumina (ceramic) Carbon Silicon Carbide POOR ptfe Stellite 18/8 stainless steel Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • Typical surface tension values:Water Mineral oil Benzene Hexane (25°C) (25°C) (20°C) (20°C) 72 dyn/cm 32 dyn/cm 28 dyn/cm 18 dyn/cm Faces with poor wettability should not be used with liquids having high surface tensions (e.g. water). Faces must also be resistant to corrosion by the sealed liquid. 7.2 Secondary Seal The secondary seal prevents leakage between the floating element of the seal and the shaft or sleeve (or the housing in the case of a seal with a stationary floating element). It may be an elastomeric 'a' ring or lip seal, a ptfe or metal wedge ring or a bellows (rubber, ptfe or metal). It must be chosen to be resistant to the chemical and thermal environment. Sliding secondary seals provide the simpler arrangement but are liable to cause fretting damage to the component against which they slide. This frequently necessitates replacement of the sleeve whenever the seal is changed. A sprayed alumina coating on the sleeve provides good resistance to fretting. Alternatively this problem can be avoided by using a bellows type seal or one in which both elements of the secondary seal are included in the "cartridge" which is obtained from the seal supplier. Soft bellows are very limited in application; metal bellows) being usually made by edge welding together preformed discs, require very sophisticated techniques and close quality control. Rolled single and multi-stream bellows are becoming increasingly more popular. 8 HEAT REMOVAL For many applications (ie except those at low temperatures and pressures when the fluid is well away from its boiling point) it is necessary to provide deliberate means of removing the frictional heat generated between the rubbing faces. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • Failure to do this may result in either: (a) Distortion of the faces leading to breakdown of the fluid film. (b) Vaporization of the liquid in the vicinity of the seal. (c) Accelerated age hardening of the elastomers used for the secondary seal. all of which may lead to premature failure. The simplest method of removing the frictional heat, applicable to most pumps, is to provide a simple flushing connection from the pump delivery over the seal and then back to the suction of the pump. In most cases, one of the connections, (either from the pump delivery to the seal or from the seal to pump suction) can be arranged internally requiring only one external pipe. When the pumped liquid is close to its boiling point (say less than 10°C below its boiling point) a simple flushing connection will generally not suffice and other measures must be taken. Some possible methods of removing the frictional heat are listed below in approximate order of increasing complexity. (d) A simple flushing connection as described above but with a restriction arranged in the return passage from the seal back to the pump suction. Hence the pressure at the seal can be higher than suction pressure thus suppressing any tendency to boil. This method is useful for applications on liquids with low boiling points. It has the disadvantage that the pressure at the seal is increased. (e) A hollow seat (e.g. Crane 'CR' type) with a suitable coolant. For hot duties (e.g. hot oil pumps) this method can be very effective since the frictional heat is removed at source. However, the coolant must be carefully chosen as too great a temperature gradient within the seat will cause thermal distortion. On some duties (e.g. refinery hot oil pumps) saturated steam can be used as a coolant. The steam must be wet; the cooling is really done by the water in the steam. (f) A simple flushing connection with a cooler in the line from pump delivery to the seal. This method is effective but the cooler has to remove quite a lot of heat. In some applications where the high temperature is required for process reasons this may be uneconomic. Alternatively, over cooling may result in freezing of high melting point fluids. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • (g) A close loop circulation. local to the seal using a 'pumping ring' available from seal manufacturers together with a small cooler in the circuit. Since this 'closed loop' is separate from the main steam, the cooler does not need to be nearly so large as in method (f) and this system is therefore attractive on large pumps. However, there is a disadvantage in that a small leak from the seal. which could be tolerated for a time causes a net inflow of liquid into the seal space causing an increase in temperature and hence possibly rapid deterioration of the seal. (Cooling jackets round the seal chamber are not recommended. To be effective it is necessary to use a thin steel liner With '0' ring seals inside the casting; the risk of leakage at what are virtually uninspectable joints is generally not acceptable). 9 DOUBLE MECHANICAL SEALS Double seals can be used in very difficult applications and properly engineered can be guaranteed to provide an effective seal. However, because of the necessary complication in auxiliary equipment double seals should generally be considered as a last resort. One exception being agitator seals with top entry shaft where liquid is not present. Double seals with a barrier liquid are usually employed. There are two basic arrangements of double seals namely:(a) The TANDEM arrangement in which the two seals are arranged in series and both are orientated so as to prevent leakage outwards, and (b) The BACK TO BACK arrangements in which the two seals face in opposite directions and are orientated so as to prevent leakage from the intermediate space into the pump on one side or out to atmosphere on the other. NOTE: Crane's seal manual also shows a 'face to face' arrangement. This is NOT a true double seal application. The outer seal is there for the sole purpose of retaining the coolant in the hollow 'U' type seat. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • 9.1 THE 'TANDEM' DOUBLE SEAL ARRANGEMENT This arrangement is of interest for high pressure applications where the combination of pressure difference and speed, exceed the capabilities of a single seal. The pressure difference can be broken down, each seal taking approximately half the total. It can also be used with LPG's or other hazardous fluids to provide an immediate alarm in the event of seal failure and a means of containing the leakage and conducting it away for safe disposal. In this case the space between the two seals should be filled with an innocuous fluid such as water/glycol. A suitable arrangement is shown in Appendix B. In each case it is necessary to satisfy the following requirements: (a) Where the tandem arrangement is used to reduce the pressure on one seal, the intermediate pressure must be controlled and adequate alarm and/or trip devices provided to protect the installation against failure of this pressure control system. (b) A reliable means should be provided to indicate if the inner seal starts to fail and leak, for example by detecting an increase in the intermediate pressure. (c) Each seal must be separately provided with suitable means of removing the frictional heat as described above. 9.2 THE 'BACK TO BACK' DOUBLE SEAL ARRANGEMENT This is the more usual double seal arrangement with a separate liquid (the sealant) supplied to the space between the seals and can be recommended in the following circumstances:(a) Handling toxic or highly pungent liquids where it is imperative to prevent leaks, or; (b) In cryogenic applications when it is difficult to prevent vaporization at the seal, or; (c) When the pumped liquid is incompatible with the seal because it is either very highly corrosive or contains abrasive solid particles. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • (d) Agitators NOTES: (1) Applications where abrasive solid particles are present can often be more simply satisfied by providing a flushing stream inside the seal of an acceptable clean fluid. (2) In many so called slurry duties, the solid content is completely harmless and non-abrasive e.g. paraxylene slurry, because it is soft like snow. For the full advantages to be gained from the 'back to back' double seal arrangement the following requirement must be satisfied. (e) The pressure of the sealant must be maintained at approximately one bar above the internal pressure at the seal (normally suction pressure) and generally trip and/or alarm devices should be provided to protect the installation against failure of this pressure. (f) A reliable means should be provided to indicate if the inner seal starts to fail and leak (e.g. pressure drop or loss of level in a closed system or increased flow in an open system). (g) Means must be provided for the removal of the frictional heat from the two seals - generally this means a circulation system for the sealant. The Bingham cryogenic pump (J Type head gear) provides an elegant solution to these problems. The pump is a vertical type and a chamber is arranged at the top in which the pump fluid is deliberately caused to exist in the vapor phase (by not lagging it and in some cases even fitting heaters). The sealant (usually a light oil) between the two seals is then pressurized by a simple head tank which is pressure balanced to the vapor space. Leakage of oil from the system is detected by a float operated level alarm in this head tank. Cooling is achieved by heat transfer into the pumped fluid. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • 10 EXTERNAL QUENCH FACILITIES An external auxiliary gland, a 'lip-type' seal or a simple throttle bush can be fitted thus providing an enclosed space outside the seal into which a quench fluid can be fed. This facility should be provided in the following cases:(a) Very large pumps (say over 100 kW). (b) Hot pumps (say over 1500C). (c) Cold pumps (where the boiling point of the liquid is below O0C at atmospheric pressure). (d) When the fluid being pumped contains solids, it solidifies or forms crystals in contact with air. (e) With highly corrosive liquids (Note: water quench should NOT be used with some very strong acids since the addition of water can increase the corrosion rate). (f) All highly flammable liquids. (g) Any duty where the pump cannot conveniently be taken off-line rapidly in the event of a seal failure. On all duties handling flammable liquids above their auto-ignition temperature, a permanent steam quench should be provided. On cold duties operating below O°C a permanent quench facility using methanol or similar solvent should be provided to clear ice buildup. On other duties listed above, the facility should be provided at the pump but not piped up as a permanent installation. NOTE: On LPG installations, the use of tandem seals with a water/glycol mixture between them (see Clause 9.1) will not only contain the leakage but can also be arranged to give warning of an inner seal failure. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • 11 APPLICATIONS NOT SUITABLE FOR MECHANICAL SEALS The following are a few notable cases where mechanical seals are not generally recommended. (a) Emergency Duties - Fire Pumps etc Mechanical seals are much more likely to fail during stopping and starting than in continuous service. Also a mechanical seal can fail rapidly and its performance changes from practically no leakage to a massive leak in a short time, although this is not normal. Again, since fire pumps in particular handle water at ambient conditions, leaks, such as can occur with a packed gland not in perfect condition, can be tolerated. Mechanical seals should NOT therefore be fitted to fire pumps, other emergency service pumps unless these run continuously, and any other pump which is called upon to operate only occasionally, but when required is essential. (b) Boiler Feed Pumps Incorporating a Balance Valve In many moderate to high pressure boiler feed pumps, particularly those of the 'ring-section' type of construction (e.g. Mather & Platt 'Plurovane'), the accumulated thrust from the impellers is resisted by a device known as a balance valve. In this device, the pressure in a chamber connected to the pump delivery adjusts itself so that the pressure rating on one side of the balance valve opposes the thrust from the impellers. For this device to function it is essential that the pump shaft is otherwise completely free to float axially. The axial float required for satisfactory operation of the balance valve and to accommodate wear can be as much as 6 mm (t·,). Very few mechanical seals will successfully cope with movements of this order, and therefore mechanical seals are not in general recommended for this type of pump. 12 RULES FOR THE APPLICATION OF MECHANICAL SEALS The following section is an attempt to lay down some simple rules for the application of mechanical seals. Generally the seal manufacturer's advice and recommendations should be sought and this should not be disregarded without very sound reasons. However, in some cases, the seal maker may not fully appreciate the operating conditions, properties of the fluids etc. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • Therefore all cases, where we question whether he has made the optimum choice of materials or arrangement of seal, should be discussed between the seal maker, the pump vendor and the user. When any of the following rules or limitations appear to be contravened; it should be insisted, as a minimum requirement, that the seal maker supports his solution with evidence of successful operation in closely similar applications where we question whether he has made the optimum choice of materials or arrangement of seal, should be discussed between the seal maker, the pump vendor and the user. When any of the following rules or limitations appears to be contravened; it should be insisted, as a minimum requirement, that the seal maker supports his solution with evidence of successful operation in closely similar applications. (a) Limits A general limitation can be applied that the product of shaft speed in rev/sec, shaft or sleeve diameter at the seal in mm and differential pressure in bar should not exceed about 105. (b) At differential pressures greater than 10 bar 'balanced' seals should be used. (c) External flushing lines should be at least 10 mm bore to reduce the possibility of blocking and should be routed so as to avoid air or vapor locking. (d) With volatile liquids, if a single seal is used, the temperature of the liquid in the immediate vicinity of the seal should be AT LEAST 10°C less than the boiling point of the liquid at the pressure which exists at the seal. This should be achieved by one of the methods described in Clause 8. (e) With liquids which are solid at ambient temperatures the seal housing and the clamping plate should be steam jacketed and not just steam traced. (f) Generally, double mechanical seals should not be used except as a 'last resort' because of the complication. A combination of a restrictor and a mechanical seal is preferred. The mechanical seal seals to atmosphere: the restrictor, which can be a close clearance bush or a lip seal prevents excessive leakage of the sealant or flushing fluid into the pump. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • (g) Double seals in the 'back to back' arrangement SHOULD be used in the following circumstances. (1) (2) Where the pumped liquid is highly corrosive and it is not economic to make all the external parts of the pump in the vicinity of the seal of resistant material. (3) When the fluid contains abrasive solid particles and it is not possible to use the simpler arrangement of a flush inside the seal with a suitable clean fluid. See Clause 12(f) above. (4) (h) Where the pumped liquid is very toxic or gives off highly pungent odors. When handling liquefied gases at temperatures below -50°C unless the particular pump manufacturer can demonstrate successful experience with a single seal. Where 'back to back' seals are employed the following requirements are essential:(1) The sealant must be compatible with the process, non-toxic, noncorrosive and not be itself a difficult material to seal. (2) The sealant must be maintained between the two seals at a pressure greater than the pressure on either side (usually 1 atmosphere or more). (3) If the pressure is controlled by instruments or other devices which can mal-function, an alarm device should be provided to give warning if it does fail. (4) When necessary, deliberate provision must be made for the removal of friction heat from both seals. This is most conveniently done by circulating the sealant. (5) If the sealant is circulated by an independently driven pump, an alarm device should be provided to warn against failure of the pump. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • (6) (j) A device should be provided to give warning of failure of the inner seal (e.g. by detecting loss of sealant from a closed system). Double seals in 'tandem' may be used in the following circumstances: (1) Where the pressure to be sealed against is too high for one seal. In this case the pressure in the intermediate space should be RELIABLY controlled at approximately mid way between the sealed pressure and atmospheric. This can often be most easily arranged with a controlled leak-off of pumped fluid. Arrangements to alarm and/or trip on failure to monitor the correct pressure should be provided. (2) As a means of containing leakage of very hazardous fluid such as liquefied flammable gases. In this case the intermediate space should be filled with a suitable innocuous fluid such as water/glycol mixture. A pressure alarm should be provided to indicate failure of the inner seal and provision should be made to contain the leakage and direct it to a flare system or other means of safe disposal. (k) In any case in which tandem seals are used, provision must be made to remove the frictional heat from BOTH seals. (m) Pumps handling flammable liquids above their auto-ignition temperature or above 200oC should be provided with steam quenching external to the seal. (n) Pumps operating continuously at temperatures below O0C should be provided with facilities to quench the outside of the seal with methanol or similar solvent to clear ice build-up. (p) It is good practice to provide all pumps handling flammable liquids with an external throttle bush, so limiting the leakage in the event of a seal failure and facilitate the provision of quench facilities if found necessary. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • (q) Mechanical seals should not be fitted to; Fire pumps or any other emergency pumps, Pumps used only occasionally, Boiler feed, or other multi-stage pumps fitted with balance valves. 13 DEALING WITH SEAL FAILURES 13.1 Problems The previous pages present an hypothesis of seal operation. What makes seals fail? Either a lack of understanding of the conditions at the seal leading to a wrong design or not adhering to the condition laid down in their design. Problem areas are the following: a) Material Selection If one of the materials in the seal is attacked by the fluid handled, the seal will fail in a short period. All seal manufacturers nowadays keep a wide selection of material with which it is possible to avoid material problems. Neglecting those failures which are caused by chemical attack, actual materials may lead to wear, due for example, to the non-wettability of the rubbing pair (Stellite and water do not go together). b) Lack of Liquid at the Seal This can be due to running a pump dry, forming a gas lock near the seal so that liquid is not present at the interface, poor venting by supplying vapor instead of liquid or adding too much heat in the seal. Many seals are fitted with pumping rings which pump the liquid round an external cooler. The thermal conductivity of the seal materials and the geometrical layout are also important in removing heat from the faces. c) Hot Running Hot running is most likely to occur when the fluid supply is not readily available at the seal due to either a bad mechanical design or the cooling circuit being inoperative. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • d) The Presence of Solids Due to the narrow gap between the seal faces, which is essential for a seal to operate well, the presence of solids is always detrimental. e) Speed A fairly low speed is needed to establish hydrodynamic conditions, the exact value depending on the fluid handled. The upper limit is determined by heat removal. f) Seal Geometry When the faces fail to be flat due to mechanical or thermal distortion or fail to be parallel due to insufficient flexibility in the support, the seal will leak. (g) Old Age Plastic elements of seals e.g. "0" rings in Viton have a shelf life of less than 5 years. The installed life is even less. (h) Secondary Failures Secondary failures occur due to fretting of the secondary elements against the shaft sleeve leading eventually to leakage or due to excessive heat causing plastic elements to deteriorate. (j ) Surge Pressures Surge pressures experienced mainly when a pump is switched off are responsible for a large number of seal failures. The high pressures and reverse pressures caused (water hammer) are seldom considered at the design stage. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • 13.2 Records & Failure Analysis Before any attempt can be made in improving seal life, knowledge must exist on which part of a seal fails, how often they fail and why they fail. To do this plant records are essential. It should be noted that good records are the main clue in establishing the cause of many a failure, not only that of seals, but also that of bearings, valves for reciprocating compressors and many other items. A good record should contain not only the actual running hours but also a description of the failed element. However, even in the absence of the description, a statistical analysis can be carried out to establish the category of failure experienced. One of the most useful qualities of analysis methods is the Weibull analysis. See Bibliography Ref (2). This analysis permits by a statistical treatment of achieved performance to obtain a value ''β' which classifies the type of failure. This analysis also provides LIO and mean life. LIO represents the life which is survived by 90% of the population. It is well defined in the rolling contact bearing industry, where the expected life is calculated from a bearing operating conditions (temperature) and the bearing load. Attempts have been made to classify seals the same way. However seal failures are usually infantile mortality or at random and in these cases LI0 loses much of its significance. Most seal failures can be attributed to short and random interruptions in the conditions which occur at the seal, examples for this are, pumps running dry, seal flush failing or seal cooling devices not being commissioned. From a Weibull analysis the following conclusions can be drawn. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • 13.2.1 A high ''β' ( >2.7) This means wear-out. (a) If the mean life is adequate - accept; if not, re-design the part or parts suffering the wear. (b) If the failures on-line are embarrassing, change the item at more frequent intervals. 13.2.2 A ''β' of about I means failures are due to random effects. (a) If the LIO life is adequate accept. (b) If not, try to quantify the random occurrences. It should be noted that a replacement on a routine basis will not improve the failure on-line rate. 13.2.3 13.3 If ''β' is less than 1 then infantile mortality is the reason for failure, examine each cause of failure and examine seal environment. Replacement on a routine basis will tend to increase the failure rate rather than improve it! Maintainability The correct installation and adjustment of mechanical seals is essential, yet often difficult or even impossible to achieve. One reason is that most pumps were designed for packed glands and mechanical seals were fitted as an after-thought. It is hoped that, in future, pump and seal designers will co-ordinate their efforts better. Some pump designers have done this - but it costs more e.g. Chesterton "System 1" pump. A partial step in this direction has been taken by the introduction of the cartridge seal where all the critical adjustments are carried out in the workshops. A complete seal, as a unit, can be fitted to a pump or agitator. Spares policy is often to hold component parts of seal and assemble on site. It is a procedure which can lead to problems if seals are assembled in situ from spare parts. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • Standardization of seals will also be of benefit. At present seals are made in many sizes even though some of them are not readily available! Standardization would also minimize spare part holdings. 13.4 Other Solutions Sometimes a solution to difficult seal problems is to use a canned magnetic or electric motor with wet or dry stator, depending on the fluid handled. Vertical cantilever shaft pumps without seals are also proving popular on atmospheric tanks SELECTED BIBLIOGRAPHY The published literature on mechanical seals is very extensive and rapidly growing. This short bibliography lists a number of general reviews that cover the whole field of radial face seals and, through their extensive bibliographies, provide a key to the literature on more specific aspects. In addition reference is made to two recent papers (No 6) that produce a new important evidence on the mechanism of lubrication of seal faces, and one paper (No 7) that lists a number of seal arrangements that have been used successfully on chemical process plants. (1) BS Nau 'Hydrodynamic lubrication in face seals', British Hydrodynamic Research Association, BHRA Report TN843, 1965. A useful review on the controversial issue of the mechanism of lubrication in face seals. (2) BS Nau 'Mechanical seals guide', BHRA Report TN904, 1967 A general treatment of the fundamental design principles. (3) LVH Bernd 'Survey of the Theory of Mechanical Face Seals' Part I Characteristics of Seals. Lubrication Engineering, 1968, 24 479-484 Part II Friction and Wear. Part III Dynamic and interfacial fluid effects. Lubrication Engineering 1968, 3!:.. 597-604 Lubrication Engineering 1968, 24 525-530 Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • An excellent review giving an extensive list of literature references. (4) E Mayer 'Mechanical Seals' Iliffe Books 1969 This is an English translation of Mayer's Axiale Gleitringdichtungen' 1966, the only book devoted to mechanical seals. (5) J G Pape 'Fundamental Aspects of Radial Face Seals' PhD Thesis Technische Hogeschool, Delft 22.10.69 (in English). The last Chapter of this thesis ('Conclusions and Design Direction') is reproduced in BHRA Rep. No, TNI046, March 1940. ( 6) ( a) J G Pape 'Fundamental Research on a Radial Face Seal' ASLE Trans 1968, !l, 302-309. (b) BA Stanghan-Batch 'Face Lubrication in Mechanical Seals' I Mech E Tribology Convention 1971, Paper C59/71. These papers are important as they produce convincing evidence that hydrodynamic lubrication of face seals is induced by waviness of one of the seal faces. (7) C Jackson 'Practical Guide to Mechanical Seals' Hydrocarbon Proc 1968, 47, 100-109. An interesting review of practical sealing arrangement on process plant pumps by a Monsanto engineer. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • APPENDIX A MECHANICAL SEAL BALANCE Considering the forces acting on the floating element of the seal. (a) PI acting to the right π/4 (B 2 - A 2) (b) P2 acting to the right π/4 (A 2 - C 2) (c) The spring force acting (d) The mean face pressure /4 (B 2 - C 2). Therefore: The mean face pressure = PI (B 2 - A 2) + P2 (A 2 - C 2) (B 2 - A 2) + SPRINGFORCE π/4 (B 2 - A 2) = P2 + (PI - P2) x (B 2 - A 2) + Contribution (B 2 - C 2) from Spring Force (B 2 - A 2) (B 2 - C 2) IS CALLED THE BALANCE FACTOR Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • [t defines the extent to which the seal face pressure is affected by the pressure difference across the seal. In a normal 'unbalanced' seal the balance factor = 1.1 approx. In a normal 'balanced' seal the balance factor = 0.7 approx.. APPENDIX B USE OF TANDEM SEALS ON LPG OR OTHER HAZARDOUS FLUIUS Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • NOTES: (B1) NORMAL OPERATION Slight vapor leak of pumped fluid carried over in sealant circulation and released to flare. (B2) FAILURE OF OUTER SEAL Loss of sealant detected by low level alarm on pot. (B3) FAILURE OF INNER SEAL Major leak will cause pressure rise in sealant pot detected by high pressure alarm. Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com
    • Refinery Process Stream Purification Refinery Process Catalysts Troubleshooting Refinery Process Catalyst Start-Up / Shutdown Activation Reduction In-situ Ex-situ Sulfiding Specializing in Refinery Process Catalyst Performance Evaluation Heat & Mass Balance Analysis Catalyst Remaining Life Determination Catalyst Deactivation Assessment Catalyst Performance Characterization Refining & Gas Processing & Petrochemical Industries Catalysts / Process Technology - Hydrogen Catalysts / Process Technology – Ammonia Catalyst Process Technology - Methanol Catalysts / process Technology – Petrochemicals Specializing in the Development & Commercialization of New Technology in the Refining & Petrochemical Industries Web Site: www.GBHEnterprises.com