Pressure Systems, Pressure Relief Streams & Protective Devices, Pressure Vessels

GBH Enterprises, Ltd.

Process Engineering Guide:
GBHE_LEP_0214

Pressure Systems, Pressure Relief Streams
& Protective Devices, Pressure Vessels

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Process Engineering Guide:

Pressure Systems, Pressure Relief
Streams & Protective Devices,
Pressure Vessels

CONTENTS

1

PRESSURE SYSTEMS

1.1
1.2
1.3

INTRODUCTION/SCOPE
GENERAL REFERENCES
RESPONSIBILITIES
1.3.1 SITE RESPONSIBLE ENGINEER
1.3.2 PRESSURE SYSTEMS INSTRUCTIONS

2

PRESSURE RELIEF STREAMS AND PROTECTIVE DEVICES
2.1
2.2

INTRODUCTION/SCOPE
ADDITIONAL RESPONSIBILITIES
2.2.1 FORMAL DESIGN REVIEW OF PRESSURE RELIEF
STREAMS (& ASSOCIATED RELIEF EQUIPMENT)
2.2.2 REGISTRATION
2.2.3 PERIODIC INSPECTION

3

PRESSURE VESSELS
3.1

INTRODUCTION/SCOPE

3.2

3.2.1 FORMAL DESIGN REVIEW OF PRESSURE VESSELS
3.2.2 REGISTRATION
3.2.3 PERIODIC INSPECTION


1

PRESSURE SYSTEMS

1.1

Introduction/Scope
A local procedure is required for the design, manufacture, installation,
Registration, commissioning, Periodic Inspection, repair, modification, rerating and operation of all the site's Pressure Equipment and Systems.
Additional working instructions may be required to support this procedure.
All site, facility and project appointments as well as responsibilities for
commissioning, operating and inspection must be listed.

1.2

General References
National and local regulations for Pressure Systems

1.3

Responsibilities
1.3.1 Site Responsible Engineer
The Site Responsible Engineer is required to read and understand the
documents listed in clause 2 and to carry out the engineering
responsibilities listed below. Carrying out the responsibilities may require
support from a Responsible Mechanical Engineer or Functional Advisor.
The Site Responsible Engineer is to make sure that:
(a)

Pressure Systems are designed, approved, manufactured,
installed, maintained, repaired, modified and re-rated in accordance
with national and international standards.

(b)

Inspection during manufacture, repair or modification is by the
relevant national or local authority or by an inspection service
approved by the Site Responsible Engineer or Project Manager as
appropriate.

(c)

Pressure Systems and Equipment is given either Registered or
non-Registered status.


Registered Pressure Systems equipment is to include:
•

all equipment covered by national or local legislation;

•

all pressure vessels except those listed as exempt from Registration;

•

atmospheric pressure Storage Tanks which are in a location where a leak
or failure could cause an Unacceptable Situation;

•

all Pressure Relief Streams and associated relief equipment with the
possible exception of items listed as exempt from Registration;

•

piping systems which are outside site boundaries or in a location that a
leak or failure could cause an Unacceptable Situation;

•

equipment other than the above such as silos, hoppers, furnaces and
components of non-registered piping systems such as bellows, piped-in
flexibles, non-return valves and spray injection desuperheaters /coolers,
which for particular reasons the site consider appropriate for Registration.

(d)

The design of new, modified or re-rated Pressure Systems
equipment which is registered is verified by a knowledgeable and
independent Design Authority to make sure that the design is
satisfactory for the specified conditions of use.
Note: Some items listed may be exempted from verification of
design at the discretion of the Responsible Mechanical Engineer or
Project Manager as appropriate.
(e)

Registered Pressure Systems equipment is Periodically Inspected
by a competent inspection service within an agreed period.
Note: The Site Responsible Engineer or nominee is to sign
or countersign a written report of the inspection and any
repairs.

(f)

Formal appointments are made of the engineers and organizations
responsible for Registration, design verification and Periodic
Inspection of Pressure Systems equipment.


1.3.2 Pressure Systems Instructions
Pressure Systems instructions for a site or facility may be issued as part of
documentation on site engineering, site operation or site safety, but
wherever they are included there is to be references to make sure
responsible people are aware of them.
The Site Responsible Engineer (where appropriate together with the
Operating Manager) is to issue, and make sure they conform with site
working instructions, Pressure Systems instructions that include the
following key topics in single or combined documents:
•
•

Pressure Relief Streams and Protective Devices;

•

Testing of relief devices;

•

Pressure vessels;

•

Atmospheric pressure Storage Tanks;

•

Silos, Hoppers, Furnaces, etc.;

•

Transport Containers and other portable tanks / vessels;

•

2

Registered Piping Systems;

Flexible Pipes or Hoses on Hazardous Duties;

PRESSURE RELIEF STREAMS AND PROTECTIVE DEVICES
2.1

INTRODUCTION/SCOPE

This section includes particular requirements for the Formal Design
Review, Registration and Periodic Inspection of Pressure Relief Streams
and Non-pressure Protective Devices which are additional to the
management systems required in all Critical Pressure Systems, and the
appointments and general responsibilities listed.


2.2

2.2.1 Formal Design Review of Pressure Relief Streams (&
Associated Relief Equipment)
(a) For all new Pressure Relief streams the following information is
submitted to the Design Authority for Formal Design Review
•

Engineering line diagram(s) showing all relevant details.

•

Process engineering documents on protection against over and
under pressure.

•

Protective Device data sheet(s), sizing calculations (including inlet
& outlet piping pressure drops), and blow off test certificates.

•

Data sheets and/or drawings of Associated Relief Equipment.

•

Detailed piping drawings of the Pressure Relief Stream with
information on discharge reaction forces, and piping flexibility loads
on the Protective Devices for systems subject to significant
variation from ambient temperature.

•

Data sheets or drawings of equipment protected by the Pressure
Relief Stream.

•

As appropriate, reports on in-service testing and inspection of
Protective Devices.

(b)

The Design Authority gives written approval of the design of all new
Pressure Relief Streams (e.g. Design Verification Certificate) before
use of the equipment.

(c)

If there should be doubts about the suitability of an Existing
Pressure Relief Stream then a Formal Design Review is requested.

(d)

For Modifications to Pressure Relief Streams the requirements of
(a) and (b) apply irrespective of whether the Pressure Relief Stream
has been previously reviewed.


2.2.2 Registration
(a)

Pressure Relief Streams and Associated Relief Equipment are
Registered and Periodically Inspected as required.

(b)

Documentation is provided in the Registration file as listed in
registry.

(c)

The identification of Pressure Relief Streams for the purpose of
Registration is initially via the schedule of Protective Devices.

(d)

For each Pressure Relief Stream and its Associated Relief
Equipment, components are identified and numbered separately
wherever it is necessary to have different schemes and intervals for
Periodic Inspection.
Note: (Figures 1 and 2) for simple and complex
arrangements

(e)

Pressure Relief Streams / Protective Devices on non-pressure
equipment such as silos are registered. Vents or panels to protect
against dust explosion are examples of this type of equipment.

(f)

Instrumented devices and systems providing protection against
excess high or low pressure (such as those which isolate
equipment from the source of pressure) are registered as Pressure
Relief Streams.

(g)

Registration is provided for non-pressure Protective Devices and
systems which protect the pressure envelope of equipment against
high or low excess temperatures, high or low fluid levels (e.g. boiler
plant) or adverse fluid composition which would cause rapid
corrosion, erosion or cracking.
Note: Other devices may control the course or rate of a
chemical reaction, and where such devices and systems
make use of instrumentation, reference should be made in
the register.


2.2.3 Periodic Inspection
(a)

Periodic Inspection is considered during Registration for all
components of Pressure Relief Streams and Associated Relief
Equipment.

(b)

Pressure Relief Streams are categorized according to the risk of
blockage or fouling due to the system contents:
•
•

Category 2 - Blockage or fouling possible but not likely.

•
(c)

Category 1 - Clean, non-corrosive duty.

Category 3 - Vulnerable to blockage or fouling.
GBHE guidance on inspection intervals for the different Categories
is considered when deciding on the maximum intervals between
Periodic Inspections.
Note: GBHE gives detailed guidance on inspection intervals for
each of the following parts of Pressure Relief Streams. - Protective
Devices; Pressure Relief Stream Piping; Associated Relief
Equipment; Non-pressure Protective Devices; Other Equipment.

(d)

Periodic Inspection of Protective Devices includes the following:


Examination of the condition of Safety Valves and Bursting
Discs as-removed and before cleaning, and judgment of how
they would have behaved on-line.



Testing of Safety Valves and other reseatable devices in-situ
or on removal (as far as is practicable) as a guide to the
pressure at which they would have operated in service. If
any device fails to operate within acceptable limits, the
cause should be investigated.



All devices are cleaned, examined, shop reconditioned, and
tested.




Maintaining Records of all observations, testing,
maintenance and replacement in the Registration file.



the Periodic Inspection interval should be reviewed based on
the observations and test results.

Note: See GBHE "Periodic Testing, Examination and
Reconditioning of Safety Valves"
(e)

Details of the routine testing, calibration and maintenance of any
Instrumented Protective Systems for Pressure Protection are
available to the Inspection Authority, and records of these are
placed in the Registration file.

(f)

Pressure Relief Stream Piping is examined for blockage of the main
flow passages and accumulation of debris and it is ensured that
any drains, purge connections and instrument tappings are clear.
The pipework and its supports and restraints should also be
inspected.

(g)

All other equipment such as scrubbers, separators, flare stacks and
relevant ancillaries to these items are to be inspected and tested to
ensure their continuing ability to meet the design requirements of
the Pressure Relief Stream.

(h)

Associated Relief Equipment is inspected to check that orifice sizes
have not enlarged by such means as erosion or corrosion that
unauthorized changes in equipment have not been made and that
the design basis of the Pressure Relief Stream has not been
otherwise altered.

(j)

The complete Pressure Relief Stream is inspected before
commissioning (or re-commissioning after overhaul) to check that it
has been assembled as designed. A record that this inspection
should be kept in the registration file.


3

PRESSURE VESSELS
3.1

INTRODUCTION/SCOPE

This section includes particular requirements for the Formal Design
Review, Registration and Periodic Inspection of Pressure Vessels which
are additional to the management systems required, for all Critical
Pressure Systems, and the appointments and general responsibilities.
For more detailed guidance contact GBHE: ’Pressure Equipment’

3.2

3.2.1 Formal Design Review of Pressure Vessels

(a) For new and Modified Pressure vessels the following information is
submitted to the Design Authority for Formal Design Review:
•

A complete set of design calculations. Calculations
should include for cyclic duty and state design life if
calculations exist.

•

A complete set of drawings.

•

Other documents required to complete the description
of the design.

•

A mechanical data sheet, where applicable.

•

Documentation (for example a Design Verification
Certificate) listing the design conditions, with
references to other relevant documents.

(b) The Design Authority carries out a Formal Design Review of the
Pressure Vessel to confirm that it is suitable for the conditions given in
(a), and in particular that:


•

the appropriate code design procedures have been followed.

•

any non-code design procedures are appropriate and
correct.

•

appropriate non destructive testing and pressure testing has
been specified.

•

no essential design requirements have been omitted.
Note: Formal Design Review is primarily concerned with the
integrity of the pressure envelope, but may by agreement be
extended to cover other aspects (such as the loads imposed
on the shell from internal trays of distillation columns).

(c) Formal Design Review certification is issued before any new, Modified,
re-rated, or replacement Registered Pressure Vessel is returned to
service (for Modifications, the review need cover only those parts
affected by the changes).

Note: Repairs to Pressure Vessels should restore them to
their original design and specification using original or
equivalent materials, fabrication & welding standards,
heat treatment, etc. Otherwise the work is treated as a
Modification.
(d) Formal Design Review is waived for small low pressure vessels
(where stored energy is the only hazard) only if all of the following
apply:
•
•
•
•
•

the contents are non-flammable, non-toxic gases and/or
liquids.
the design pressure does not exceed 15 bar g.
the product of design pressure (bar g.) and gross volume
(m3) does not exceed 25 bar m3.
exemption is approved by the Site Responsible Engineer (or
Project Manager) after careful consideration of all relevant
factors.
details are recorded in the Registration file.


(e) A Formal Design Review is considered if there are doubts about the
suitability of an existing Pressure Vessel, such as where the
Registration file does not contain adequate information.
(f) Adequate documentation and design confirmation is obtained for
proprietary Pressure Vessels. Formal Design Review is required for
vessels with potential hazards because of pressure and/or the nature
of their contents, but alternatives may be considered for small series or
regularly produced equipment such as intercoolers, aftercoolers and
line filters on low hazard duties. (see GBHE Ordering and Design
Verification of Proprietary Vessels)

3.2.2

REGISTRATION

(a)

All Pressure Vessels (with the possible exception of those listed in
Appendix A) are Registered and Periodically Inspected as required
by GBHE, and also that:

•

Pressure Vessels are identified from flowsheets, line diagrams and
equipment lists, taking care not to overlook additions arising from plant
modifications.

•

used Pressure Vessels designed for other duties are not Registered and
put into service until they have been:
- approved by the Design Authority with a Formal Design Review;
- thoroughly inspected and approved by an inspection authority.

(b)

Documentation is provided in the Registration file as listed in
registry.


3.2.3

PERIODIC INSPECTION

(a) Periodic Inspection is considered during Registration.
(b) Pressure Vessels and associated equipment should be allocated inspection
grades based on the ability to predict behavior in service and / or the
expected rate of deterioration.
(c) GBHE guidance on inspection intervals for the different grades is considered
when deciding on the maximum intervals between Periodic Inspections.
(d) Periodic Inspection of Pressure Vessels includes:
•

checking the condition by visual inspection, supplemented as
necessary by other techniques and measurements to determine
fully the extent of loss of thickness, pitting, cracking or other
defects;.

•

consideration of both internal and external features;

•

internal inspection by entry where access is possible, except where
satisfactory alternative means of internal examination are available
and where the Site Responsible Engineer waives entry;

•

Hydraulic (not pneumatic) pressure testing when it is the only
practical way of demonstrating integrity (e.g. for complex tubular
arrangements). Pressure testing only confirms the ability of the
equipment to hold pressure at the time of the test and does not
provide equal reassurance of long term integrity to that gained from
thorough examination of surfaces. As such it is not a generally
preferred means of examination for any equipment.

Note: The in service pressure testing of equipment instead
of inspection requires a written procedure and Risk
Assessment.


(e)

Pressure Vessels which have limited life (due to high temperature creep,
or to fatigue cracking due to pressure cycling or frequent start up and shut
down) are categorized and inspected as advised.

(f)

All non-registered Pressure Vessels are inspected externally at
appropriate intervals. Adequate inspection and maintenance should take
place to ensure their continuing fitness for purpose.

(G)

Specialist advice is sought for Pressure Vessels of particular construction
and / or containing certain types of chemicals.


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