1 Scope 1.1 Newly constructed plant piping and pipelines 1.2 Existing plant piping and pipelines 1.3 Field and Shop Fabricated Piping 1.4 Shop Fabricated, and Skids 1.5 Exclusions 1.6 Lay Up
2 References
3 Definitions
4 General Requirements 4.1 New Pipelines 4.2 Existing Pipelines 4.3 New Plant Piping 4.4 Instrument piping 4.5 Tie-Ins 4.6 Alternate Tests 4.7 Piping Not tested 4.8 Atmospheric lines 4.9 Valves as Test Boundaries
5 Piping Design Requirements 5.1 Vents 5.2 Drains 5.3 Supports 5.4 Temporary Supports
6 Pressure Testing of Plant Piping 6.1 Test Pressure 6.2 Test Time 6.3 Exposed Joints 6.4 Specific Tests for Specific Services 6.5 Test of Existing Piping .6.6 Proof Test
7 Hydrostatic Testing 7.1 Safety 7.2 Pneumatic Testing 7.3 Static Head 7.4 Test maintenance 7.5 Protection From Overpressure 7.6 Test Diagrams 7.7 Test Preparation 7.8 Test Procedures 7.9 After Completion Of Pressure Test
8 Pneumatic Testing 8.1 Test Boundaries 8.2 Cold Weather Pneumatic Testing 8.3 Test Media 8.4 Test Pressure 8.5 Method.8.6 Precautions 8.7 Instrument Air Piping
9 Pressure Testing for Minor Repairs 9.1 Threaded Piping 9.2 Socketweld Piping
10 Pressure Testing of Miscellaneous Piping And Components 10.1 Reinforcing Pad Test 10.2 Hot Taps 10.3 Jacketed Lines 10.4 Sanitary Sewers
11 Lay-Up 11.1 General 11.2 Carbon Steel And Low Alloy Steel Equipment 11.3 Lay-up Procedures 11.4 Stainless Steel Equipment 11.5 Special Requirements 11.6 Hydrostatic Test Fluid Preparation 11.7 Safety
1 Scope
1.1 Newly Constructed Plant piping and Pipelines
This article defines mandatory requirements governing pressure testing of newly constructed plant piping and pipelines which are designed and constructed in accordance
with ASME B31.1, B31.3, B31.4, or B31.8 code as applicable. This article supplements ASME B31 and other applicable codes.
1.2 Existing Plant piping and Pipelines
This article covers mandatory requirements for testing existing plant piping and pipelines for revalidation purposes or after repairs.
1.3 Field and Shop Fabricated Piping
The requirements of this standard apply to field/shop fabricated piping systems and field fabricated equipment.
1.4 Shop Fabricated, and Skids
This standard does not cover pressure testing of new, shop fabricated equipment such as vessels, tanks, heat exchangers and skid mounted piping which are purchased in
accordance with the applicable specification.
1.5 Exclusions
Exclusions are listed in context below as applicable.
1.6 Lay Up
This standard establishes requirements for hydrostatic test fluid composition and subsequent lay-up procedures for new, revalidated and refurbished storage tanks,
pressure containing equipment, plant piping and pipelines. The purpose of this standard is to minimize corrosion damage to equipment due to delay in start up after hydrostatic testing.
2 References
Reference is made in this standard to the following documents. The latest issue, amendments and supplements to these documents shall apply unless otherwise
indicated. When a project is in effect, the version of engineering and design codes, specifically ASME B31 codes, shall govern, as specified in the contract for that project.
SABIC Engineering Standards (SES)
P01-E16 Safety Instruction Sheets
P01-E21 Fire Protection Water Systems
Industry Codes & Standards
American Petroleum Institute
API RP 520 Part I – Sizing, Selection, and Installation of Pressure Relieving Devices in
Refineries
American Society of Mechanical Engineers
B31.1 Power Piping
B31.3 Process Piping
B31.4 Pipeline Transportation system for liquid hydrocarbons and other liquids
B31.5 Refrigeration Piping
B31.8 Gas Transmission and Distribution Piping Systems
B31.9 Building Services Piping
SEC VI Recommended Rules for the Care and Operation of Heating Boilers
SEC VIII D1 & 2 Boiler and Pressure Vessel Code
National Board of Boiler and Pressure Vessel Inspectors
NB 23 National Board of Inspection Code
3 Definitions
Hydrostatic Test. A pressure test conducted using water or other approved liquid as the test medium.
Lay-up. Storage, as it applies to corrosion protection of piping between testing and actual use.
MSDS. Manufacturers Safety Data Sheet
Owner. The owner of the facility, as defined in ASME B31 codes.
Pneumatic Test. A pressure test conducted using air or other approved gas as the test medium.
Hydrostatic-Pneumatic leak test : It is a combination of hydrostatic and pneumatic test The requirements shall be as per clause 345.6 of ASME B31.3
Revalidation Test. A pressure test performed to prove the integrity of existing pipelines or plant piping.
Strength Test. A pressure test at an internal pressure determined in accordance with this standard and the applicable code to verify the integrity of the piping systems for service at the design pressure. This definition applies to ASME B31.8. The same definition is a hydrostatic leak test in ASME B31.1 and B31.3, and a proof test in ASME B31.4.
Tightness Test. A pressure test to ensure tightness of the piping system (i.e. no leaks in the system) at the test pressure.
Sensitive leak Test: A low pressure test conducted using gas as medium as per clause 345.8 of ASME B 31.3
Service leak Test: This is a test conducted using the service fluid as the test fluid. The test pressure shall be operating pressure of the system. This test is applicable only to piping in category D fluid service at the Owner’s option. For other details refer to clause # 345.1(a) of ASME B 31.3.
4 Pressure Testing and Lay-up Procedures in Plant Piping and Pipelines General Requirements
4.1 New Pipelines
Every pipeline, after construction and prior to initial operation, shall successfully pass a
hydrostatic test. The test pressure shall be in accordance with minimum requirements of
ASME B31.4 or B31.8 as applicable.
4.2 Existing Pipelines
Every existing pipeline, after repairs or alterations have been made that affect the integrity
of the pressure containing parts, shall successfully pass a hydrostatic test. The test
pressure shall be in accordance with the requirements of the applicable code.
4.3 New Plant Piping
All newly constructed plant piping, and prior to initial operation unless exempted by this
standard, shall be subjected to a hydrostatic strength test in accordance with the
requirements of this standard and the appropriate ASME B31 code.
4.4 Instrument piping
Instrument take-off piping and sampling system piping up to the first block valve, shall be
pressure tested together with the piping or equipment to which it is connected.
4.5 Tie-Ins
Provision shall be made to facilitate conducting a strength test to the tie-in welds of new
piping to either new or existing system. The test pressure shall be based on the minimum
required by code if the tie-in is to an existing system.
4.6 Alternate Tests
Alternate testing may be used when the standard test is not practical. The use of
alternative testing is a SABIC decision, and approval must be in writing. The alternate test
is 100% radiography supplemented with other testing. Radiography in lieu of a pressure
test is generally backed up with a sensitive leak test, in accordance with the appropriate
ASME B31 code.
4.7 Piping Not tested
Pressure testing of the piping system is not required for the following cases and under the
condition that welding does not require post weld heat treatment (PWHT):
a. Seal welds of threaded connections, if the threaded connections have been
previously strength tested.
b. Attachment welds of non-pressure containing parts to pressure containing parts
which have been previously strength tested.
4.8 Atmospheric lines
Piping such as drains, vents and piping downstream of pressure relieving devices that
discharge directly to the atmosphere are exempt from pressure testing unless the line has
a listed design pressure in excess of 100 kPa. However, atmospheric lines shall be
carried out visual inspection.
4.9 Valves as Test Boundaries
When valves are used for blocking or isolating hydrotest sections, the differential pressure
across the valve seat shall not exceed the seat test pressure, as specified by the
manufacturer. At no time shall the test pressure exceed the rated seat test pressure.
5 Piping Design Requirements
5.1 Vents
Vents shall be provided at all high points in the piping system. Cross-country or
submarine pipelines may be exempted if a scraper will be used ahead of the test water to
purge air from the lines before the test pressure is applied.
5.2 Drains
Drains shall be provided at all low points of the piping system, excluding submarine and
buried pipelines. They shall be immediately above check valves which are in vertical
position.
5.3 Supports
The piping system shall be analyzed to foresee whether temporary supports are required
during hydrostatic testing to limit the sustained longitudinal stresses to acceptable limits
by the appropriate ASME B31 code. When temporary supports are required, the
requirement shall be noted on the appropriate piping or pipeline drawing. This information
shall be included on the test loop diagrams.
5.4 Temporary Supports
Expansion joints and spring hangers or spring supports shall be provided with temporary
restraints where needed to prevent excessive travel or deformation under the test loads.
6 Pressure Testing of Plant Piping
This section defines specific requirements related to pressure testing of plant piping, such
as test pressure, duration, etc.
6.1 Test Pressure
Minimum Test Pressure. The test pressure shall not be less than the minimum test
pressure per ASME B31.3 paragraph 345.4.2. For “fire fighting water lines” test pressure
shall be in accordance with paragraph 17.5 of SES F02-E01.
6.2 Test Time
The test pressure shall be maintained for a minimum of 30 minutes. The pressure must be
maintained for a sufficient time to determine that there are no leaks.
6.3 Exposed Joints
All joints including welds shall be left un-insulated and exposed for visual leak detection
during the test. Coating and priming of such joints are not allowed unless approved by the
Owner. The pipe itself may be primed and coated to a final coat.
6.4 Specific Tests for Specific Services
6.4.1 Lube and seal oil piping shall be pressure tested with oil. The test pressure shall
be 1.5 times the design pressure or 690 kPa, whichever is the greater.
6.4.2 Underground process piping shall be tested prior to backfilling. The test pressure
shall be maintained for a minimum of 2 hours while the joints are inspected for leakage. If for justifiable safety reasons the line must be back-filled, then the joints
shall remain exposed during testing.
6.4.3 Flare lines NPS 24 and larger may be pneumatically tested in accordance with ASME B31.3, if there is insufficient support available, or the quantity of water
necessary is unreasonably large.
6.4.4 Vacuum Service. Piping in vacuum service shall be pressure tested to 1.5 times the differential external pressure, but not less than 100 kPa.
6.4.5 Plant utility piping shall be tested with a service leak test as described for Category D, as defined in ASME B31.3, subject to owners approval.
6.4.6 Instrument lead lines between the root valve and the instruments, shall be subjected to the same pressure test as the piping or equipment with the pressure
rated instruments connected. Elements that may be damaged shall be removed or disconnected for the duration of the test.
6.5 Test of Existing Piping
When existing plant piping is subjected to hydrostatic pressure testing, the test pressure
shall not exceed 1.5 times the design pressure, or is limited by the actual wall thickness.
6.6 Proof Test
Certain services may be required to pass a proof test. The proof test pressure is the
pressure that will create a stress equal to 90% of the yield stress, regardless of the design
pressure of the system. With unused corrosion allowance, and mill tolerance, the proof
test is usually limited by the flange rating, or the shell test pressure.
7 Hydrostatic Testing
7.1 Safety
Pressure testing safety shall be followed during pressure testing.
7.2 Pneumatic Testing
Pneumatic testing is not permitted without written approval of SABIC.
7.3 Static Head
The effect of the static head of the testing liquid shall be considered when determining the
effective test pressure of any elements within a tested system.
7.4 Test maintenance
The test pressure shall be maintained for a sufficient time to determine that there are no
leaks.
7.5 Protection From Overpressure
All systems (piping and equipment) while being hydrostatic tested shall be protected from being over pressured by the following:
7.5.1 A relief valve of adequate capacity set to relieve at 5 percent above the test pressure shall be installed. Sizing of these relief valves used for testing shall follow the requirements of API RP 520, Part 1. The relief valve shall be tested, dated, and tagged within one month prior to the test.
7.5.2 Manual Valve. In addition to the pressure relieving device, a bleed valve shall be provided to protect the piping and equipment from overpressure. The bleed valve
shall be readily accessible in case immediate depressurization is required.
7.5.3 Isolation Valve. An isolation valve shall be provided between the pressure testing manifold and the system being tested. The isolation valve shall be rated for the
manifold test pressure when in the closed position.
7.6 Test Diagrams
Hydrostatic test diagrams and test procedures shall be prepared by the responsible engineering group and made available to the Inspection Group prior to conducting the test. The test diagrams and procedures shall include the limits of piping and equipment included in each hydrostatic test, test pressures, test temperature, test fluid, line flushing requirements, and safety precautions. It is recommended that the test diagram shall include as much piping length as possible at one time for system test.
7.7 Test Preparation
7.7.1 Site Preparation
a. An approved test procedure shall be available at the site prior to commencing any pressure testing activities.
b. New piping systems shall be flushed clean of loose scale and debris or scraped prior to commencement of pressure testing. Care shall be exercised to ensure all pipe spools are internally clean before installation.
c. Soft seated valves and control valves shall not be installed until after the lines have been thoroughly flushed.
d. Components which interfere with filling, venting, draining or flushing shall not be installed until after line flushing and pressure testing are completed.
These include orifice plates, flow nozzles, sight glasses, venturies, positive displacement and turbine meters and other in-line equipment. The Void may be created due to the removal of these components from the line during testing/flushing activities shall be suitably filled with temporary spool(s).
e. Pressure gages and pressure recorders shall be calibrated before the tests.
(i) The calibration interval shall not exceed one (1) month. Calibration certificates shall be made available to Inspection personnel prior to commencement of the pressure test. Stickers shall be applied indicating the latest calibration date.
(ii) All gages shall have a range such that the test pressure is within 30 to 80% of the full range.
(iii) A minimum of two pressure gages are required for the test system. One pressure gage shall be on the test pump and the other(s) on the test system. Their accuracy shall be within 5% of one another.
(iv) When large systems are tested, Inspection personnel will determine the need for additional gages.
(v) Recording gages shall be used where it is necessary to keep a permanent record, for example, when the test duration exceeds four hours, or otherwise as required by this standard.
f. Expansion joints and spring hangers or spring supports shall be provided to prevent excessive travel or deformation under the test loads. with temporary restraints where needed
g. All weld joints of the piping system to be tested shall be ensured free of rust and other foreign matter
h. The requirement of hydro test water quality shall be as per para11.1,11.2,11.4 and 11.6 as applicable.
7.7.2 Equipment Excluded from Pressure Test
The following list defines the equipment that shall be excluded from the pressure test loops.
a. Strainers and filter elements
b. Pressure relieving devices, such as rupture disks and pressure relief valves
c. Locally mounted indicating pressure gages, where the test pressure may exceed their scale range, thermowell, control valves, orifice meter, flow
nozzles, sight glasses, venturies, rotameters, positive displacement meters and other in-line instruments.
d. Equipment that cannot be drained
e. Check valve disc removed for swing check ; piston & springs shall be removed in case of lift check valves.
7.7.3 Isolation of Test Sections
a. Paddle blinds or spectacle blinds shall be used to isolate the test sections. When this is not practical, closed block valves (gate, globe, plug, ball) may
be used to isolate equipment or piping sections. SABIC approval is required when a block valve is used for isolating test section. When a block valve is used for isolating test sections, the differential pressure across the valve seat shall not exceed the seat test pressure during pressure testing and shall not exceed the rated seat pressure during tightness test. Both sides of this valve shall be protected by relief valves during the test.
b. All valves, excluding those used for sectioning or blocking test, shall be in the open position.
7.7.4 Vents and Drains
a. Vents shall be provided at all high points in the tested system as needed.
b. Excluding submarine and buried pipelines, drains shall be provided at all low points in the system and immediately above check valves in vertical lines.
c. The disc of the check valves should be removed and securely attached to the outside of the check valve prior to the pressure test.
7.7.5 Temporary Connections and Supports
a. Temporary connections shall be provided for de-pressurizing and draining of the system to the sewer or disposal area.
b. Temporary supports shall be installed prior to hydrostatic testing, and flushing of the piping. These supports shall not be removed until after the system has been fully drained.
c. The structural support system design for stacked equipment shall be verified for hydrostatic loads prior to testing.
7.8 Test Procedures
7.8.1 Testing : The test shall be conducted in accordance with the applicable code. In addition, the following requirements shall apply.
a. Filling and pressurizing shall be done on the upstream side of check valves in the system. The test fluid shall be injected at the lowest point in the system to minimize entrapped air. All vents shall be open during filling.
b. After the test pressure is reached and before commencement of inspection of the system, the isolation valve between the temporary test manifold, or piping and the piping, or equipment under pressure test shall be closed and the test pump disconnected.
c. During the application of the test pressure, all in-line valves if not used as test isolation valves shall be in an open position.
7.8.2 Test Records shall be made for each test by entries on pressure test report, and the applicable “Safety Instruction Sheet” per SES P01-E16.
7.9 After Completion Of Pressure Test
After pressure testing has been successfully completed and approved by the SABIC Inspector, the following operations shall be performed.
7.9.1 Draining of Test Fluid. Release of pressure and draining shall be done on the downstream side of check valves. All vents shall be opened before draining to
facilitate drainage and to prevent formation of a vacuum. No test fluid shall remain in low spots. Pressure shall be released in a manner and at a rate so as not to
endanger personnel or adjacent property/ equipment.
7.9.2 Test Vents and Drains. Vents and drains used only for the pressure test shall be plugged and seal welded.
7.9.3 Removal and Reconnection of Components. All temporary items installed for testing/flushing purposes (for example, manifolds, valves, blinds, spacers,
supports, temporary gaskets/bolts) shall be removed.
a. Items that were removed from testing shall be reinstalled.
b. Items, such as instrument air tubing, check valve discs which were disconnected before testing shall be reconnected.
c. Isolation valves closed for the test purposes and that are required to be in the open position for process reasons shall be opened. If the valve cavity has a drain, the cavity shall be drained.
d. Ensure to remove Retaining pins of spring support after testing and flushing and prior to commissioning of the system.
8 Pneumatic Testing
8.1 Test Boundaries
Close control shall be maintained to limit the stored energy (PV) and the reaction force (PA) of gas in any single test system. The stored energy (PV) level shall be determined by multiplying the pneumatic test pressure, in kPa, by the volume, in cubic meters, of the proposed test system. The reaction force (PA) shall be determined by multiplying the pneumatic test pressure, in kPa, by the largest cross-sectional area, in square meters, in the proposed test system. The maximum energy level (pressure x volume) recommended is 12500 or maximum reaction force (pressure x area) recommended is 2500. Approval by SABIC is required to exceed these limitations.
8.2 Cold Weather Pneumatic Testing
8.2.1 Minimum Temperature. No piping shall be pneumatically tested when the metal temperature is below 15 C, with three exceptions.
a. First, for materials that have been impact certified, the test temperature may be as low as the impact certification temperature.
b. Second, if the wall thickness is less than 25 mm and the test pressure does not exceed 15 percent of the allowable working pressure of the pipe, then the metal temperature may be as low as minus 29C.
c. Third, the AISI Series 300 austenitic stainless steels may be tested at any temperature above minus 100 C.
8.2.2 Testing With Vessels. Where non impact tested vessels are in the circuit, perform the test at 15C or above. Impact tested vessels may be included in the test down
to their impact test temperatures.
8.2.3 Deviations. Any deviations from these rules must be approved by SABIC.
8.3 Test Media
Use utility air, instrument air or nitrogen for all systems requiring a pneumatic test when
indicated.
8.4 Test Pressure
The listed test pressure for piping to be pneumatically tested shall be 110 percent of the design pressure.
8.5 Method
8.5.1 Low Pressure Tests. Pneumatic testing shall be carefully supervised. When the
test pressure is 150 kPa, or less, the initial pressure may be raised directly to the
test pressure.
8.5.2 High Pressure Tests. When the test pressure is greater than 150 kPa, the system
shall be initially pressured to 150 kPa. All welds and connections shall be
inspected for leaks by applying a leak detecting solution to all of the joints and
checking for bubbles. The pressure shall then be increased gradually to 50
percent of the test pressure. This pressure shall be maintained at least 10
minutes. The pressure shall be further increased in steps of approximately 10
percent of the test pressure until the required test pressure has been reached.
8.5.3 Design Pressure Test. After holding the test pressure for 10 minutes, the test
pressure shall be reduced to the design pressure and held for a sufficient time to
permit an inspection for leaks of all piping welds and connections.
8.6 Precautions
8.6.1 Degree of Test. Pressurizing lines and equipment for tests may be done during normal working hours to the extent allowed as follows. All pneumatic pressure
tests in excess of the following conditions shall be performed outside of normal working hours.
8.6.2 No Area Isolation. Pneumatic tests at less than 350 kPa may be performed for all pipe sizes during normal working hours without isolating the area involved.
8.6.3 Medium Size Testing. Pneumatic tests up to 700 kPa may be performed during normal working hours without isolating the area involved, provided no piping in
the system under test is larger than NPS 12.
8.6.4 Isolation Required. Systems containing piping larger than NPS 12 may be pressured up to 350-700 kPa, but not over one-half the final test pressure, for
preliminary examination and leak testing. The final pneumatic tests will be performed outside normal working hours.
8.6.5 Included Vessels. Any pressure vessel included in any system to be pneumatically tested or pressured during normal working hours shall have had a previous code hydrotest, and shall not be pressured to more than 110 percent of allowable working pressure.
8.6.6 Off Hours Testing. Pressurizing above the limitations may only be done during off-shift or on weekends. Only personnel associated with the testing shall be
allowed in the area.
8.7 Instrument Air Piping
8.7.1 Test Medium. The instrument air system shall be service tested with instrument air. When this is not available a utility air source supplied by a non lubricated
compressor may be used.
8.7.2 Terminal connections shall be disconnected allowing air to blow through to ensure that all lines are clean before testing. The instrument air sub header block
valves adjacent to the main header shall be closed, and the union immediately downstream from the block valve broken open before testing the main instrument
header.
9 Pressure Testing for Minor Repairs
This section defines pressure testing requirements for existing facilities which are
subjected to minor repairs:
9.1 Threaded Piping
When minor repairs are made to threaded piping, all of the original requirements, such
as thread engagement, and seal welding, shall be met. Any joints involves in repairs,
shall be inspected for leakage after pressurization.
9.2 Socket weld Piping
When socket weld piping has been repaired, and the Owner has determined that a retest
is impractical, the piping may be pressure tested with its own product at its operating
pressure when the following requirements are met:
a. A request of NDT in lieu of pressure testing is processed as detailed
b. Qualified welders and welding procedures are used
c. The weld gap verified and welding witnessed by the responsible Operation Inspection Unit
d. Welds shall be either magnetic particle (MT) or dye penetrant (PT) tested
10 Pressure Testing of Miscellaneous Piping And Components
The following piping components shall be tested as follow:
10.1 Reinforcing Pad Test
Reinforcing pad of welded branch connections shall be pneumatically leak tested with air at 175 kPa through a tapped vent hole (weep hole), and examined for leaks using a soap solution at a reduced pressure of 20 to 35 kPa. The tapped vent hole shall be packed with heavy grease after the completion of the test.
10.2 Hot Taps
Hot taps must be tested before the coupon is cut.
10.3 Jacketed Lines
10.3.1 Jacket Test. The internal and external pipe of all jacketed lines shall be tested. The internal line shall be leak tested on the basis of internal or external pressure whichever is critical. All welds in internal piping in jacketed spools must be tested during shop fabrication before being covered by the jacket.
10.3.2 Field Weld. When a field weld is necessary in the internal pipe, a second test shall be performed in the field to prove the integrity of the field weld. A small
section of jacket must be left off until the test is complete to enable the test crew to visually inspect this weld,.
10.4 Sanitary Sewers
Sanitary sewer systems within buildings shall be tested per requirements of the Uniform
11 Lay-Up
Plumbing Code (UPC).
11.1 General
11.1.1 Water PH Level. Do not use any water for hydrostatic test if the pH is less than 7
and the sulfate reducing bacteria (SRB) counts are greater than 10²
per ml unless
approved by SABIC. When water from more than one source is to be used
ensure that mixing the streams will not cause scaling. Treat the test fluid to
control corrosion and bacteria when applicable.
11.1.2 Schedule. Minimize the time between introducing hydrostatic test water and
commissioning the equipment. Schedule the hydrostatic test as close as possible
to the start-up date.
11.1.3 Worst Case. Design the hydrostatic test and the lay-up procedure to protect the
most corrosion-susceptible material in the system.
11.2 Carbon Steel And Low Alloy Steel Equipment
11.2.1 Treatment of Hydrostatic Test Water
a. Oxygen Scavenger. The addition of an oxygen scavenger to the hydrostatic test
water shall be required where the equipment contact time with water is likely to
exceed 14 days. Treat the water before it enters the system. An oxygen
scavenger shall be added unless there is a 100% certainty that the water will be
drained completely within 14 days. Use batching scrapers or a slug of nitrogen
to separate the air in the system from coming in contact with the treated water,
and then fill the system with water injecting sufficient oxygen scavenger to
maintain a minimum sulfite residual concentration of 20 mg/L.
b. Microbial Control. In addition to oxygen scavenger treatment, microbial control
of the hydrostatic test water shall be required if the equipment contact time with
water is likely to exceed 90 days. Research should be done for current
recommendations on biocide selection or treatment for pH adjustment.
11.3 Lay-up Procedures
11.3.1 Lay-Up Types. Lay-up, in accordance with one of the following procedures, shall
be required for all equipment as a part of the hydrostatic test, unless the start-up
is ensured to be within 60 days from introduction of test fluid. Lay-up shall be
required for heat exchangers unless start-up is ensured within 14 days of
commencing hydrostatic test. Exceptions are noted below:
11.3.2 Wet Lay-up.
a. Establish and maintain throughout the system a minimum residual
sulfite level of 20 mg/L in the water. This includes dead legs. Analyze
water sample(s) for residual levels of sulfite at the location most remote
from the inlet. Record the test results in the hydrostatic test report.
Once minimum residuals are verified, keep the system tightly closed to
air entry. Repeat tests and ensure chemical residuals every six months
during lay-up. If a leak occurs or air enters the system, lay-up the
system again after completing repairs.
b. Maintain the system under a positive pressure of 2% to 10% of the
operating pressure, but not exceeding 350 kPa, using nitrogen, a sweet
hydrocarbon gas, or hydraulic pressure of the treated water. Install
thermal relief for systems that are to be laid up with hydraulic pressure.
If the operating pressure is lower than atmospheric pressure then
maintain a positive pressure at maximum allowable pressure but not
exceeding 350 kPa.
c. Use pressure gages with an appropriate scale range for the pressure
being measured to monitor the low positive pressure of the system
during lay-up.
11.3.3 Dry lay-up
a. Remove the water from the system. For facilities other than pipelines,
drain the system completely, sweep and mop as required to ensure that
no visible traces of water remain. For pipelines, water removal is
performed by scraping.
b. Dry the system to a dew point of -1 °C or less at all exit points by
vacuum drying, or blowing dry air or nitrogen through the system. If
necessary, use dehydrating chemicals. Shut in the system for not less
than 12 hours to allow any remaining moisture to come to equilibrium
with the dry air. Check and ensure that the exit dew points measured
are at or below -1 °C. Repeat the drying procedure if the dew point has
risen above -1 °C.
c. When the required dew point is reached, pressurize the system with dry
air or nitrogen having a dew point lower than -1 °C. Shut in the system,
maintain and monitor per during the lay-up period.
11.3.4 Inert Gas Lay-up
a. For inert gas lay-up upon completion of a successful final hydrostatic test,
displace the hydrostatic test water with nitrogen or sweet gas until no water
drains out of the system. Shut in the system under positive pressure until
commissioning and start-up.
b. Do not open vents to atmosphere to drain hydrostatic test water out of a
system and attempt to replace the air with an inert gas by either repeated
pressuring or sweeping. However, in the case of long pipelines, displacement of
air by sweeping with inert gas-driven scrapers shall be acceptable.
c. Microbial control is not required even though there is some residual water in
the system.
11.3.5 Ambient Lay-up
a. Use ambient lay-up only if all of the following conditions apply:
(i) Drains are available at all low points to ensure complete
removal of water.
(ii) Corrosion allowance has been provided.
(iii) Pitting can be tolerated.
(iv) Particulate rust can be tolerated.
b. If raw water or sea water has been the hydrostatic testing fluid, drain
the test water and spray rinse the system with water containing less
than 500 mg/L total dissolved solids. Use batch scraping with water
slugs containing less than 500 mg/L total dissolved solids, for pipelines.
c. After removal of all visible water, close the system to prevent the entry
of sand or rain water.
d. Install a vacuum breaker prior to ambient lay-up if the system is to be
pressure tight.
11.3.6 Other lay-up methods. The use of vapor phase corrosion inhibitors and other layup
methods require
prior written
approval of
SABIC.
11.3.7 After Lay-Up. After demothballing, commission and start up heat exchangers
within 14 days, and other equipment within 60 days.
11.4 Stainless Steel Equipment
The following shall apply for the hydrostatic testing of equipment made of and
equipment containing pressure retaining parts made of AISI 300 and 400-series
stainless steels.
11.4.1 Requirements for Testing Fluids
a. Chloride content of the hydrostatic test water. The maximum chloride
content for hydrostatic test water in contact with stainless steel shall be
limited to 50 mg/L. Verify at the time of injection into the system, except
for cases defined below.
b. Adjust the pH of the hydrostatic test water to 10.5 +/- 0.5 at the time of
injection into the system, by adding soda ash (Sodium carbonate) or
caustic (Sodium hydroxide).
c. In addition if the equipment contact time with water is likely to exceed 4
days, treat the hydrostatic test water with oxygen scavenger.
11.4.2 Lay-Up Time Limit. If the equipment contact time with water is likely to exceed 14
days, microbial control, and lay-up of the system, shall be required.
11.4.3 Lay-Up Limit. After demothballing, commission and start up the stainless steel
equipment within 14 days.
11.4.4 AISI 400 Steels. Do not use ambient lay-up for equipment made of AISI 400series
stainless steels unless the ambient relative humidity is controlled to be less than 40% at all times.
11.5 Special Requirements
11.5.1 Product Pipelines
a. Cross-country or sub-sea pipelines in gas or refined hydrocarbon
product service, regardless of the contact time with water, require the
following procedures. An oxygen scavenger shall be added to the
hydrostatic test water. Use batching scrapers and/or a slug of nitrogen
to separate the air in the system from coming in contact with treated
water, and then fill the system with treated water by injecting sufficient
oxygen scavenger to maintain a minimum sulfite residual concentration
of 20 mg/L.
b. Dry out. The above pipelines shall be dried to a dew point of -1C for
corrosion control unless a lower dew point is specified for other
reasons. The drying shall be done as soon as possible after the
hydrostatic test and the system shall be kept under dry lay-up until
commissioned.
11.5.2 Galvanized Piping. Treat galvanized steel pipe per paragraph 11.1 and lay-up per
paragraph 11.2.
11.5.3 Non-Metallic Piping-.No lay-up procedure is required for totally non-metallic
systems (for example, RTR and PVC pipe).
11.5.4 Alternate Test fluid. Use a liquid other than water for pressure testing if the
operating fluid or the equipment is likely to be adversely affected by incomplete
removal of water. Such a fluid shall not have a flash point below 54 °C.
11.5.5 Coated and Lined Systems. Water shall not require any treatment if used to
pressure test completely internally coated or lined equipment, or systems entirely
fabricated with non metallic materials.
11.6 Hydrostatic Test Fluid Preparation
11.6.1 Injection Rate. Inject oxygen scavenger and other treatment chemicals
continuously at a rate that will provide the specified concentration while filling the
system for the hydrostatic test.
11.6.2 Chemical Compatibility. Where multiple treating chemicals are required, ensure
that the chemicals proposed for use are compatible with one another. Use
separate proportioning pumps for each chemical to avoid adverse reactions.
Chemicals shall not be mixed prior to injection.
11.6.3 Injection Monitoring. Monitor chemical injection rates on site using displacement
gauges.
11.7 Safety
11.7.1 MSDS’S. Follow procedures outlined in any MSDS’s for additives for handling,
storage, and mixing of the chemicals to be used for hydrostatic test water
treatment.
11.7.2 Safety Equipment. Provide an effective eye wash station and emergency shower
at the mixing site of the chemicals.