Pressure Testing Presentation

AN OVERVIEW OF PRESSURE TESTING Presentation 2006

Index Introduction Definition & Purpose Application Types of Pressure Tests Safety Requirements Governing Standards General Requirements

Determine Test Pressure Flushing / Cleaning Pressurizing Leak Detection Methods Test Duration Depressurize & Disposal Lay-Up

INTRODUCTION  Pressure

Testing is one of the quality control methods that is universally known and accepted as a means of demonstrating the fitness of a pressurized component for service.

DEFINITION & PURPOSE Pressure Testing is defined as a test conducted to any pressure component or equipment by subjecting it to an internal pressure using liquid or gas.  Purpose    

To ensure strength of the pressure component To ensure tightness of the system To detect and eliminate any defects To show or prove that no defect exists

Pressure = Force per Unit Area = pounds per sq. inch = psi

APPLICATION

Pipe Spools

Plant Piping

Pipeline

Pressure Vessels & Tanks

Heat Exchangers

Valves

Non-Metallic Pressure Component

TYPES OF PRESSURE TESTING A.

Hydrostatic Testing is a pressure test using water or other approved liquid as the test medium.

B.

Pneumatic Testing is a pressure test using air or other approved gas as testing medium.

Safety Failure During Test

Safety Failure During Test

SAFETY REQUIREMENTS  Follow

the requirements of G.I. 2.102

Obtain work permit from operating organization.  Cordon off the testing area.  Only qualified personnel shall be involve.  Use only proper test equipment  Avoid striking or working on equipment being tested while under pressure.  Piping or equipment must be adequately supported.  Controlled pressure rise. 

GOVERNING STANDARDS Saudi Aramco Standards      

G.I. 2.102 – Pressure Testing Safely SAES-A-004 – General Requirements for Pressure Testing SAES-A-007 – Hydrostatic Testing Fluids and Lay-Up Procedures SAES-L-150 – Pressure Testing of Plant Piping and Pipelines 04-SAMSS-048 – Valve Testing & Inspection Requirements SAEP-327 – Disposal of Wastewater from Cleaning, Flushing, and Hydrostatic Test Water.

Industry Standards  

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

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ASME B31.3 – Process Piping ASME B31.4 – Pipeline Transportation Systems for Liquid Hydrocarbons & Other Liquids ASME B31.8 – Gas Transmission and Distribution Piping Systems API 598 – Valves Inspection and Testing. Or any Standard stated in the P.O. API 600 – Valves API 602 – Valves ASME B16.34 – Valves

GENERAL REQUIREMENTS  Approved

Written Test Procedure  Test Package  Pre- Test Inspection  Test Equipment  Calibrated Instruments

Equipment & Instruments Required  Test

Manifold – tested to at least 20% above test pressure.  Pressure Gauge – calibrated within one month of the test and the range shall be such that test pressure shall be within 30% to 80% of its range.  Relief Valve – calibrated within 1 week of testing. Set at 5% above test pressure.  Pressure Pump

Test Manifold For Hydrostatic Testing Relief Valve

Vent Valve

Pressure Gauge

Block Valve

Bleeder Valve Hand Pump

DETERMINING TEST PRESSURE A.

The hydrostatic test shall produce a hoop stress in the pipe of 90% of the specified minimum yield strength or SMYS. (SAES-L-150). P = 2 x t x 0.9S D Where:

P = test pressure, psig

S = SMYS, pounds per sq. in. D= outside diameter of pipe, in. t = wall thickness, in. (less mill tolerance) Note: Design Temperature & Test temperature considerations are critical. When Design Temps exceed Test Temps, see ASME B31.3, 345.4.2 Pt = 1.5 x PSt S

Determining Test Pressures B. C. D. E. F. G.

By flange rating or valves in the line (from ASME B16.5 & ASME B16.34) By operating pressure (for service test) By 1.5 times the design pressure (minimum required by ASME B31.3 paragraph 345.4.2) For Pneumatic Testing it is 110% of the design pressure as per ASME B31.3 paragraph 345.5.4. 200 psig for firewater lines. (SAES-B-017 Par.12.6). Refer to SAES-A-004 & SAES-L-150 for other equipment & testing condition.

SAMPLE PRESSURE TEST PACKAGE REVIEW (CALCS) VERIFY “LIMITING FACTOR” CALCS: 1. Piping calcs ... How to do it. Where to go.

P = 2 x t x 0.9S / D Proposed Test Pressure = 1125 psig in your test package (limiting factor Class 300 Flange) Material (piping spec) is ASTM A 106 Grade B (Not Grade A ... Be very careful checking) S or SMYS is Found in ASME B31.3 Appendix A Tables (pg 430/596) = 35 KSI D is listed on SIS Sheets as 2” , 24” & 16” ... Use outside diameters of 2.375, 16” & 24” T is listed on SIS Sheets as: 2” = Sch 80 or .218” wall, 16” & 24” = Std wall or .375” T include Mill Tolerance ... 87.5% of Nominal for seamless pipe, or .01” for rolled plate T = .218” x .875 or .191” for 2” pipe & .375” x .875 or .328” for 16” & 24” pipe

Calcs as follows: 2” – 2 x .191 x .9 (35,000) / 2.375 = .382 x 31,500 = 12,033 / 2.375 = 5,066 psig 16” – 2 x .328 x .9(35,000) / 16 = .656 x 31,500 = 20,664 / 16 = 1292 psig 24” – 2 x .328 x .9(35,000) / 24 = .656 x 31,500 = 20,664 / 24 = 861psig

REVIEW RESULT: WE REJECT TEST PACKAGE & REQUIRE TEST PRESSURES BE DROPPED TO “LIMITING FACTOR” or 861 psig. SIS Sheets must be revised to show corrections.

COMMON “LIMITING” FACTORS FOR PRESSURE TEST 1. Flange “fitting” pressure ratings (ASME B16.5, B16.47 for large diameter, API Work ratings) 2. Valve Flange Ratings (ASME B16.34) 3. Large Diameter Piping (Check calcs quickly on all 12” +) 4. Schedule 20 or 30 piping is checked very closely 5. Special SA Considerations for Systems (Flare Headers, etc) 6. Testing against a closed valve (1.1 times pressure rating of Valve, not 1.5 times rating as allowed in Valve body tests) Learn to do 2-minute calcs per package and quickly review calcs. Keep a fast check sheet available for pressure ratings. Never look Up the same stuff on a regular basis. BE EFFICIENT!!! CORROSION ALLOWANCE FINDINGS ... WHOSE JOB IS IT? SPEED DRILL & CLASSROOM PRACTICE (LIMITING FACTOR)

FLUSHING 

The piping system is filled up with water and at low points of the system water is released. In case of pipelines, scraper is used ahead of the Hydrotest water.



In Pneumatic testing, the system is filled with air and with all exit points open, check the cleanliness of the system by using a clean target paper.

FLUSHING CONCERNS 1. Low point accumulated water & debris. 2. Where is the low point? Low point drain? 3. Using gravity and air to “blow dry” lines.  Blow from “high points” (Dry Rag, debris) 4. Disagreements about adequacy of flushing.  Torch Slag controversy for “set-on” weld bosses  Discoloration of water, noted heavy deposits  DO NOT FORGET THE VALVES (DRAINS)  Check Valves & other locations for problems  RANDOM “Valve Checks” after flushing ... You’ll be surprised what you will find.

PRESSURIZING  

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Test fluid injected at the lowest point in the system Gradually increase the pressure in the system to 50% of the required test pressure, or 25 psig for pneumatic test. (QC HOLD POINT ... Equalization) 20% increment for hydrostatic test and 10% increment for pneumatic test. Disconnect the pressure pump and allow the pressure in the system to stabilize for a period of 10 minutes or 5% of the test time whichever is longer. Use “Tape” for pressure readings over time of test. Press into test report as “hard evidence” of passing tests. Also train your QC to be extremely efficient.

Plant Piping Isometric Drawing

LEAK DETECTION METHODS  Visual

Inspection Method: During and after the completion of test pressure, conduct a full visual inspection of the system. All welds, threaded/flanged connections, and including valves must be inspected for leaks.  Pressure Drop Method: After stabilization record the exact pressure and monitor during the test period. This method is particularly used in testing pipelines or any 24 hour recorded testing.

Pressure Chart

Pressure/Temperature Chart

Leak Detection  In

Pneumatic Testing – all joints are inspected by applying a mixture of soapwater solution or any commercial leak detectors.

TEST DURATION 30 minutes minimum for hydrostatic test of plant piping. (SAES-L-150 Para. 7.2)  In pipelines, 2 hours strength test plus 24 hours recorded tightness test. (SAES-L-150 Para. 8.3)  4 hrs for firewater lines.(SAES-B-017 Para. 12.6)  As long as necessary for inspection of leaks in pneumatic testing.  For Valves, as per applicable standard such as API 598, MSS-SP80, or AWWA. 

Depressurizing & Test Water Disposal  Upon

completion of a successful hydrostatic test release the pressure through the vent valves and bleed valves. The test liquid shall be slowly drained with vents open to prevent collapse of system. (Random Witness Point)

 Test

fluid shall be disposed in accordance with SAEP-327. The disposal procedure must first be approved by the Environmental Protection Department of Saudi Aramco.

LAY-UP (Refer to SAES-A-007)  Lay-up

rules (14 & 60 day ... LL)  Ambient Lay-Up  Dry Lay-Up  Wet Lay-Up  Inert Gas Lay-Up  Use of Vapor-Phase Corrosion Inhibitors