Pipeline Systems PIP PLSC0019 Specification for Pressure Testing HDPE Plastic Pipeline Systems

Transcription

1 November 2017 Pipeline Systems PIP PLSC0019 Specification for Pressure Testing HDPE Plastic Pipeline Systems

2 PURPOSE AND USE OF PROCESS INDUSTRY PRACTICES In an effort to minimize the cost of process industry facilities, this Practice has been prepared from the technical requirements in the existing standards of major industrial users, contractors, or standards organizations. By harmonizing these technical requirements into a single set of Practices, administrative, application, and engineering costs to both the purchaser and the manufacturer should be reduced. While this Practice is expected to incorporate the majority of requirements of most users, individual applications may involve requirements that will be appended to and take precedence over this Practice. Determinations concerning fitness for purpose and particular matters or application of the Practice to particular project or engineering situations should not be made solely on information contained in these materials. The use of trade names from time to time should not be viewed as an expression of preference but rather recognized as normal usage in the trade. Other brands having the same specifications are equally correct and may be substituted for those named. All Practices or guidelines are intended to be consistent with applicable laws and regulations including OSHA requirements. To the extent these Practices or guidelines should conflict with OSHA or other applicable laws or regulations, such laws or regulations must be followed. Consult an appropriate professional before applying or acting on any material contained in or suggested by the Practice. This Practice is subject to revision at any time. Process Industry Practices (PIP), Construction Industry Institute, The University of Texas at Austin, 3925 West Braker Lane (R4500), Austin, Texas PIP Member Companies and Subscribers may copy this Practice for their internal use. Changes or modifications of any kind are not permitted within any PIP Practice without the express written authorization of PIP. Authorized Users may attach addenda or overlays to clearly indicate modifications or exceptions to specific sections of PIP Practices. Authorized Users may provide their clients, suppliers and contractors with copies of the Practice solely for Authorized Users purposes. These purposes include but are not limited to the procurement process (e.g., as attachments to requests for quotation/ purchase orders or requests for proposals/contracts) and preparation and issue of design engineering deliverables for use on a specific project by Authorized User s client. PIP s copyright notices must be clearly indicated and unequivocally incorporated in documents where an Authorized User desires to provide any third party with copies of the Practice. PUBLISHING HISTORY November 2017 Issued Not printed with State funds

3 November 2017 Pipeline Systems Table of Contents PIP PLSC0019 Specification for Pressure Testing HDPE Plastic Pipeline Systems 1. Scope References... 2 Industry Codes and Standards Definitions Requirements Safety Test Pressure and Duration Testing Medium Test Segment Isolation Pre-test Notifications and Permits Recording Instruments Conducting the Pressure Test Documentation Process Industry Practices Page 1 of 13

4 1. Scope This standard provides minimum requirements for performing pressure tests using a liquid medium on non-reinforced HDPE plastic pipe intended for all service types (e.g., hydrocarbon, produced water). 2. References Applicable parts of the following industry codes and standards shall be considered an integral part of this Practice. The edition in effect on the date of contract award shall be used, except as otherwise noted. Short titles are used herein where appropriate. Code section references below are specific to the code editions in effect at the issuance of this Practice. Industry Codes and Standards 3. Definitions American Society of Mechanical Engineers (ASME) ASME B Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard American Petroleum Institute (API) API Standard Welding of Pipelines and Related Facilities owner: The party who owns the facility or pipeline wherein the piping will be used purchaser: The party who awards the contract to the supplier. The purchaser may be the owner or the owner's authorized agent. supplier: The party responsible for providing the testing services 4. Requirements 4.1 Safety Testing shall be performed in accordance with owner and local regulatory requirements The test area shall be clearly identified by using safety barriers and posted signs Only personnel involved with the pressure test (e.g., inspecting the equipment, taking the necessary readings) shall be permitted within the test area All personnel and equipment not actively involved in the test shall maintain a minimum distance of 15.2 m (50 feet) from any pressurized pipe or fitting Owner shall notify people who live or work within 30.4 m (100 feet) of a pipeline segment to be tested about the testing activities before pressurization of the pipe is started. Process Industry Practices Page 2 of 13

5 4.1.6 If the distances specified in Sections and are not possible, owner shall ensure that people and equipment not actively involved in the test are maintained as far away from the test area as possible If testing is to be performed in high traffic areas, consideration should be given to providing additional signage and/or providing public notice of the testing activities Before the start of testing, a Job Safety Analysis shall be conducted for all personnel within the vicinity of the test Except if used for instrumentation lines, hoses sized 25 mm (1 inch) and greater and pressurized to greater than 0.68barg (10 psig) shall be staked at a minimum of every 7.6 m (25 feet) Mechanical connections (e.g., hose connections, instrument lines, hammer unions) shall be protected with whip checks or equivalent All components (e.g., piping, hoses, fittings) shall be inspected for proper pressure rating All mechanical connections shall be exposed for leak examination For underground connections, joints, and seals exposed for observation during the test, sufficient backfill material shall be placed between the joints and over the pipe to prevent movement because of thrust forces. Comment: Large amounts of exposed piping can result in large temperature related pressure changes, making a stable test difficult to achieve Personnel responsible for the tests shall have relevant and adequate training and experience in pipeline hydrostatic and/or pneumatic testing For preventing over pressurization, a Pressure Relief Device (PRD) shall be installed with the set point equal to the maximum allowable test pressure plus 1.4 barg (20 psig). The PRD shall be tested before conducting the pressure test Direct heating of any pipe contained within the test section shall not be permitted during the test If a leak is discovered, the test section shall be depressurized before repairing the leak Because leakage at a butt fusion joint can indicate imminent catastrophic rupture, if butt fusion leakage is discovered, the test section shall be depressurized immediately Appropriate environmental, health, and safety (EHS) protocols shall be specified and followed including but not limited to the following: a. Energy isolation (i.e., Lock Out Tag Out) b. Hazard Assessment & Personal Protective Equipment (PPE) c. Hot work d. Excavation and trenching e. Pre-Job Planning Process Industry Practices Page 3 of 13

6 4.2 Test Pressure and Duration Pressure tests shall be held for 1 hour after the 4 hour expansion phase (see Section ) The piping material temperature shall not be higher than the greater of: a. 38 C (100 F) b. the material s long term hydrostatic design basis temperature For DOT regulated, non-reinforced plastic pipelines, the maximum test pressure shall not be greater than 14.8 barg (215 psig) Owner shall determine and furnish the following pressure test parameters: a. Maximum Piping Material Temperature b. Maximum test pressure c. Minimum test pressure d. Duration of test d. Location of test equipment f. High point, low point, and measurement elevations The pressure test parameters shall be recorded in the Pressure Test Record The effect of elevation on test pressures shall be considered for tests where elevation change is greater than 30.5 m (100 feet) Testing pressures shall be in accordance with piping materials manufacturers limitations. 4.3 Testing Medium Unless otherwise specified in the contract documents, municipal water shall be used as the testing medium If municipal water is not available or if another type of water is specified in the contract documents, the water used for the pressure test shall be tested and shall be in accordance with the following requirements: a. Total Suspended Solids: Less than or equal to 100 ppm b. Total Dissolved Solids (TDS): Less than or equal to 2,000 ppm c. ph: Between 6 and If ambient temperatures are expected to be less than 4.4 C (40 F) during the test period, methanol or another freezing inhibitor shall be considered If use of any chemicals is expected, owner shall furnish a plan for water disposal. 4.4 Test Segment Isolation Test termination points shall be isolated from adjacent pipeline facilities. Process Industry Practices Page 4 of 13

7 4.4.2 Unless otherwise instructed by the valve manufacturer, valves which are in-line for the test shall be maintained in half-open position during the test ASME code pressure vessels shall be isolated from the test An owner representative shall supervise the isolation operation and ensure the isolation has been conducted properly. 4.5 Pre-test Notifications and Permits All required state and federal notifications shall be made and permits shall be obtained before any testing starts A local owner s representative shall be consulted to determine if additional permits are required for pressure testing or water disposal. 4.6 Recording Instruments General Unless otherwise agreed by purchaser, a traditional dead weight tester (DWT) shall be used for recording the test information If a digital gauge is to be used, the gauge shall be as accurate as a traditional DWT over the entire test pressure range Field adjustments to the chart recorders shall not be permitted If the chart recorder readings differ from the DWT readings, the difference shall be noted in the pressure test documentation Pen charts that record pressure and pipe and fluid temperature shall be used for each pressure test and for pre-testing any pipe or assembly including bore pipe Ambient temperature shall be recorded with a pen chart or other recording device Pressure and temperature recording equipment shall be provided in accordance with Table 1. Table 1 - Pressure and temperature recording equipment Deadweight (Hydraulic or Electronic) Pressure Recorder Ambient Temperature Recorder Pipe Temperature Recorder Combination Pressure and Ambient Temperature Recorder NIST-certified Pressure Gauge (Backup) Required X X X X X Optional X Recorder Manifolds Recorders that connect to the pipe segment being tested shall have a piped manifold. Process Industry Practices Page 5 of 13

8 A recorder manifold shall have additional connections for the DWT and a backup manual pressure gauge A recorder manifold shall be capable of isolating all of the instruments from the pipe segment being tested Calibration Certifications Calibration certificates shall be provided for the DWT or equivalent recording device and pen chart recorders All instrument certifications shall be valid for 12 months before recertification is required Copies of all calibration certifications for pressure and temperature recording equipment shall be provided before testing begins All recording equipment shall have certification dates not greater than 6 months before the testing date Deadweight Testers Owner approved DWT may be electronic or hydraulic DWT shall be capable of measuring pressures in maximum increments of 0.1 barg (1 psi) DWT shall have the following components: a. National Institute of Standards and Technology (NIST) traceable Hydraulic Deadweight Tester b. Pressure Recorder with NIST traceable certification Pressure Recorders Pressure recorders shall be capable of recording up to a 24-hour range Pen chart recorders shall be in accordance with the following: a. 200 mm (8 inch) minimum diameter chart size. Larger charts are preferred. b. The recorder shall permit the minimum and maximum test pressures to be between 35 to 65% of the range of scale Pressure recorders shall be in accordance with the following: a. Range of scale appropriate to test pressure b. Capable of recording units of pressure as specified by the owner. c. Maximum logging interval: 30 seconds Pipe Temperature Recorders Temperature recorders shall be capable of recording up to a 24 hour range Pen chart recorders shall be in accordance with the following: Process Industry Practices Page 6 of 13

9 a. 200 mm (8 inch) minimum diameter chart size. Larger charts are preferred. b. Range of scale: 0 to 70 C (150 F) Temperature recorders shall be in accordance with the following: a. Range of scale: 0 to 100 C (200 F) b. Capable of recording units of temperature as specified by the owner. c. Maximum logging interval: 30 seconds The sensor of a pipe temperature recording device shall be installed in contact with the pipeline and located in accordance with the following: a. At a point that has protection from the sun. b. At a distance far enough from the test medium injection point so that the effect of the exposed piping on temperature is minimized. c. Backfill around the sensor shall be tamped Ambient Air Temperature Recorder Temperature recorders shall be capable of recording up to a 24-hour range Pen chart recorders shall be in accordance with the following: a. 200 mm (8 inch) minimum diameter chart size. Larger charts are preferred. b. Range of scale: 0 to 70 C or 0 to 150 F Temperature recorders shall be in accordance with the following: a. Range of scale: 0 to 100 C or 0 to 200 F b. Capable of recording units of temperature as specified by the owner. c. Maximum logging interval: 30 seconds Combination Pressure and Ambient Temperature Recorder A dual pen chart recorder may be used to record pressure and ambient temperature Each recorded line shall be clearly labeled on the chart The recording pen shall apply enough pressure to draw a heavy, consistent line on the chart In addition to a DWT (hydraulic or electronic), a back-up NIST-certified pressure gauge shall be used to ensure test pressure accuracy Recorders that connect to the pipe segment being tested shall be common on the same manifold. Process Industry Practices Page 7 of 13

10 The manifold shall have additional connections for the DWT and the backup NIST-certified pressure gauge The manifold shall be capable of being isolated from the test segment Recommendations for Charts and Chart Recorders Selection Large charts are preferred Separate charts for recording the temperature and pressure are preferable Dual or combined chart recorders are permissible If a dual pen chart recorder is used, each recorded line shall be clearly labeled on the chart The chart s scale should allow easy, identifiable reading of the recording The chart time range should be an appropriate length, typically 24 hours The recording pen should apply enough pressure to draw a heavy, consistent line on the chart. 4.7 Conducting the Pressure Test Pre-Test Preparation Before testing, completion of the following activities shall be verified for both the system to be tested and the test equipment: a. All mechanical joints are completely assembled with all necessary seals, fasteners, and gaskets properly installed b. All flange bolts are torqued in accordance with owner s specifications c. All valve body bleed vents are closed and tightened d. All non-destructive testing (NDT) has been performed in accordance with the contract documents Temporary welded assemblies including test heads used for test activities shall be examined by 100% radiographic inspection and approved in accordance with API Standard 1104 before conducting the hydrostatic test All test heads (i.e., a short section of pipe with an end cap and valves welded to the end of a section and used in the filling of pipe and controlling pressure during testing operations) shall be pre-tested a minimum of one hour to a minimum of 125% of the maximum test pressure Documentation of pressure testing and NDT shall be retained and included in the final documentation listed in Section Except as permitted by Section , all test termination points shall be isolated from the adjacent pipeline facilities and pressure vessels by blind flanges with appropriate blind flange ratings to meet or exceed the Process Industry Practices Page 8 of 13

11 pressures expected during testing, and manufactured in accordance with ASME B Skillet or spectacle blinds per ASME B16.48 which are stamped with the appropriate pressure rating or for which the material certifications are available may be used to isolate test termination points Flushing, pigging, or other means of cleaning the system to remove dirt and debris that may damage valves and regulators shall be performed before testing. Comment: Cleaning by pigging involves forcing a resilient plastic plug (i.e., soft pig) through the pipeline. Pigging should be performed using a launcher and receiver. Soft pigs are required with polyethylene pipe. Scraping finger type or bucket type pigs can severely damage the pipeline and should not be used Unless otherwise instructed by the valve manufacturer, all installed valves in the test section shall be tested in the half-open position so that the valve seats and gate segments are not required to withstand the test pressure Check valves shall be secured in the full open position or the flappers removed Valves that are only connected on one side shall have blinds or hex plugs for flanged and threaded ends, respectively Instruments and sensing lines shall be disconnected and the root valve shall be in the open position and plugged Initial Filling of Test Segment The filling or pressurization shall be performed in a controlled and steady manner and in the presence of a purchaser representative The pipe segment shall be filled with the test liquid in a manner that will ensure no air or product remains in the pipe to be tested A displacement pig shall be launched by pumping water behind the displacement pig and holding a pre-packed column of air or nitrogen in front of the pig Fill rates shall not be greater than 1.5 meters per second (5 feet per second) pig velocity If the line cannot be properly displaced of air during the filling operation, vent valves shall be installed at the high elevation points where air is likely to accumulate After the line has been filled, a minimum of 4 hours shall be permitted for the test water temperature to stabilize before strength testing. Permitting the test water to stabilize overnight is preferred Stabilization shall be complete before the strength test portion of the hydrotest. Process Industry Practices Page 9 of 13

12 4.7.3 Expansion Phase To permit gradual, acceptable expansion of the pipe during the expansion phase, the pressure shall be gradually increased by approximately 0.68 barg/min (10 psig/min) or less, until the minimum test pressure is reached Once the minimum test pressure is reached, the pipe shall be shut in and permitted to expand for one hour Additional medium shall be added once every hour for four hours to maintain test pressure During the expansion phase, continuous surveillance shall be maintained for leaks in test equipment, connections, flanges, etc When making repairs to equipment or pipe segments or tightening bolts, the pressure shall be bled down to 0 barg (0 psig) and re-pressurized after the repairs are made When the maximum test pressure is reached, the following readings shall be placed in the Pressure Test Log at a minimum of 15 minute intervals: a. Time b. Pressure (Hydraulic or Electronic Deadweight) c. Temperature (Ambient and Pipe) d. Remarks (e.g., Volume of make-up test liquid additions to maintain pressure, Pressure bleed-off, irregularities in the pen chart recordings, weather changes, etc.) Strength Test Phase After the initial expansion, the minimum test pressure shall be held for an additional hour When the target strength test pressure is reached, the duration begins and the individual responsible for conducting the test shall record the following readings at 15 minute intervals: a. Time b. Pressure (dead weight tester or equivalent) c. Temperature (ambient and pipe/test medium) d. Remarks (weather changes) e. Volume of water added or withdrawn The combined time between initial pressurization before expansion and final depressurization shall not be greater than 8 hours If the test is not completed within 8 hours, the test section shall be depressurized and permitted to relax for a minimum of 8 hours before pressurizing the test section again. Process Industry Practices Page 10 of 13

13 4.7.5 Termination of Test and Depressurization of Piping Before depressurization, purchaser shall review the data and information from the test to determine if the test was successful Unless the test period becomes greater than specified in Section , the test pressure shall be maintained above the minimum test pressure until the test is approved by the purchaser After the test has been completed, the pressure in the pipeline shall be gradually decreased at a rate not greater than 1.7 barg/min (25 psig/min) until the pressure reaches 3.4 barg (50 psig) Pass/Fail Criteria A test shall be considered passing if no visual leakage is observed, and pressure during the 1 hour strength test phase remains steady within 5% of the target test pressure If the pressure drop is greater than the allowable 5% of the target test pressure during the 1 hour strength test phase, an additional attempt may be made by re-pressurizing to the target test pressure and conducting another one (1) hour strength test phase as long as the maximum test duration specified in Section is not exceeded If the test does not meet the passing requirements within the maximum pressure test period, or if leak repairs are required, the test section shall be depressurized and remain so for 8 hours until a re-test can be attempted Dewatering 4.8 Documentation Following successful completion of the pressure test, the hydrostatic test water from the pipeline segment shall be displaced De-watering shall be performed by propelling displacement pigs through the pipeline system with air, nitrogen, or natural gas If natural gas is used to propel the displacement pig, a pre-start-up safety review shall be completed The pipeline system shall be dried in accordance with owner s requirements for the intended pipeline or facility use and product specification Displaced water shall be disposed of or directed into temporary storage for treatment in accordance with requirements furnished by the owner s representative Pressure Test Documentation The following documentation is required: a. An explanation of all pressure discontinuities, including test failures appearing on the pressure recording charts. b. The temperature and pressure recording charts from the test. The temperature and pressure recording charts shall be signed by the Process Industry Practices Page 11 of 13

14 supplier and a purchaser representative. The signatures on the charts shall verify that the charts were produced by the recorder during the pressure test. c. Documentation of any volume additions or withdrawals. d. Sufficient description to designate which pipelines were tested and the extent of pipeline (e.g., stationing, chainage etc.) included in the test sections. e. A map and/or sketch showing the locations of the test points, temperature bulb, and pressure pump See Figure 1 for a sample of documentation form DWT Data shall be provided in accordance with the following: a. A list of the pressure readings taken with the DWT showing comparable pressure recorder readings at the time of the test shall be included in the final report. b. The DWT readings shall be the pressure readings provided in the final report and used for all calculations and certifications. c. The pressure recording charts are only to document pressure continuity and shall not be provided as the official test pressure readings For pipelines with elevation differences of greater than 30.5 m (100 feet) from the highest to the lowest test points, a profile shall be included in the final report showing the elevation along the test section and at the test site Additionally, the final report shall contain but not be limited to, the following elements for each test section: a. Biocide treatment reports b. Pressure recording charts c, Deadweight (hydraulic and electronic) reading logs d. Pipe temperature recording charts or combination pressure/temperature recording charts. e. Ambient air temperature recording charts f. Calibration certificates of each piece of testing equipment utilized g. Reports covering the disposition of all test failures/leaks h. Alignment drawings showing pressure test boundaries i. Documentation of a Completed Pre-Task Safety Meeting. j. Photos of test equipment configuration and manifolds All other relevant field data taken during the test shall also be included in the final report The final report shall be forwarded to the owner within 24 hours of completion of a successful pressure test. Process Industry Practices Page 12 of 13

15 Figure 1: Sample Pressure Test Documentation Form Process Industry Practices Page 13 of 13