ASME B31.3 | B31.4 | B31.8 | SEC VIII Div.1

Hydrotest Pressure Calculator:
ASME B31.3, B31.4, B31.8
and Section VIII Div.1

The only free online tool covering all four US piping codes in one calculator. Get minimum test pressure, recommended test pressure, hold time requirements, hoop stress verification, elevation head correction, and PHMSA 49 CFR 192/195 regulatory references in one report.

⚡ B31.3 Process Piping (1.5x) 🛢 B31.4 Liquid Pipelines (1.25x) 💨 B31.8 Gas Pipelines (Class 1-4) ⚙ SEC VIII Div.1 Vessels (1.3x) 📝 PDF Report 🚫 Hoop Stress Check

Compute Minimum and Maximum Hydrotest Pressure Across All Four ASME Piping Codes

Select your code, enter design pressure, and optionally add pipe dimensions for hoop stress verification and elevation head correction.

Code Selection and Required Inputs

B31.3 for process piping inside facilities. B31.4 for crude/refined product pipelines. B31.8 for natural gas interstate/intrastate. SEC VIII for unfired pressure vessels.

psig

Maximum allowable operating pressure (MAOP) for pipelines. Design pressure for process piping. Enter as gauge pressure (psig).

ST/S

ST is allowable stress at test temperature; S is allowable stress at design temperature. Ratio capped at 6.5 per B31.3 Section 345.4.2. Leave blank for 1.0.

Optional Inputs for Advanced Checks

Pipe geometry for hoop stress verification
in
in
ft

Extra pressure at low points = 0.433 psi per foot of water head. Critical for tall systems and pipeline sections with significant elevation changes.

⚡

Select a code, enter design pressure, and calculate. Add pipe OD, wall thickness, and material for hoop stress verification. Add elevation difference for low-point head pressure check.

Why Hydrotest Pressure Calculations Differ Across US Piping Codes

Hydrostatic testing is the primary method of proving pipeline and pressure vessel integrity before commissioning and after repair in the United States. The US is home to more than 2.8 million miles of regulated pipeline under PHMSA (Pipeline and Hazardous Materials Safety Administration) jurisdiction, including roughly 300,000 miles of gas transmission pipeline and 195,000 miles of hazardous liquid pipeline. Under 49 CFR Parts 192 and 195, every segment must pass a pressure test before entering service, and every repaired segment must be retested before returning to operation. The test proves the pipeline can withstand pressures well above its maximum allowable operating pressure without leaking or failing structurally.

The critical point most engineers miss is that the required test pressure multiplier is not the same across all systems. ASME B31.3 process piping inside a refinery or chemical plant requires a minimum of 1.5 times the design pressure. An API 5L pipeline carrying crude oil under ASME B31.4 needs only 1.25 times the MAOP. A natural gas transmission pipeline under ASME B31.8 uses a multiplier that depends on the location class of the area the pipeline passes through: 1.25 times for Class 1 and Class 2 areas, and 1.4 times for Class 3 and Class 4 urban areas. A pressure vessel tested under ASME Section VIII Division 1 uses 1.3 times the MAWP. Getting the wrong multiplier is not a minor error: it is a code violation that can trigger federal enforcement action and, more importantly, leaves the system undertested with an unknown safety margin.

The US natural gas transmission pipeline network carried approximately 28 trillion cubic feet of gas in 2024, per the US Energy Information Administration. Every mile of that network required a pressure integrity test before service. The test pressure requirements are enforced by PHMSA under 49 CFR Part 192 (gas) and 49 CFR Part 195 (hazardous liquids), with civil penalties of up to $266,015 per violation per day for non-compliance.

What Is Hoop Stress and Why Does It Cap Test Pressure?

Hoop stress is the circumferential stress in the pipe wall caused by internal pressure trying to split the pipe longitudinally like a seam. The formula is sigma (psi) = P times D divided by (2 times t), where P is the test pressure in psi, D is the pipe outside diameter in inches, and t is the wall thickness in inches. This is the Barlow formula used in every US pipeline design code.

During a hydrotest, the applied pressure must stay below the level that would cause the pipe to yield. If hoop stress exceeds the Specified Minimum Yield Strength (SMYS) of the pipe material, the pipe has been plastically deformed and may be permanently damaged even if it does not visibly rupture. Common API 5L grades and their SMYS values are: Grade B at 35,000 psi, X42 at 42,000 psi, X52 at 52,000 psi, X60 at 60,000 psi, X65 at 65,000 psi, and X70 at 70,000 psi. This calculator automatically flags when the minimum required test pressure produces hoop stress above SMYS for the selected grade.

What Is the Elevation Head Correction?

When a pipeline segment has significant elevation change, the section of pipe at the bottom of a hill experiences higher test pressure than the gauge reading at the test head because the water column above it adds hydrostatic pressure. The correction is simple: add 0.433 psi for every foot of elevation difference in the system. For a pipeline section with 100 feet of elevation change, add 43.3 psi to the test pressure at the low point. Low-point fittings, valves, and flanges must be rated to handle this additional pressure without failing during the test.

Code-by-Code Breakdown: Multipliers, Hold Times, and Federal Regulatory Alignment

CodeApplicationMin Test MultiplierMax Test CapHold TimeFederal Reg
ASME B31.3Process piping in plants and refineries1.5 x design pressure x (ST/S)ST/S ratio capped at 6.510 min minimum (visual inspection)OSHA 29 CFR 1910.119
ASME B31.4Liquid petroleum pipeline transportation1.25 x MAOPTypically 1.5 x MAOP practical limit4 hours minimum new construction49 CFR Part 195 (PHMSA)
B31.8 Class 1Gas pipeline, fewer than 10 buildings/mi1.25 x MAOPNot to exceed SMYS hoop stress8 hours minimum49 CFR 192.505(a)(1)
B31.8 Class 2Gas pipeline, 10-45 buildings/mi1.25 x MAOPNot to exceed SMYS hoop stress8 hours minimum49 CFR 192.505(a)(2)
B31.8 Class 3Gas pipeline, 46-100 buildings/mi1.40 x MAOPNot to exceed SMYS hoop stress8 hours minimum49 CFR 192.505(a)(3)
B31.8 Class 4Gas pipeline, dense urban, 100+ buildings1.40 x MAOPNot to exceed SMYS hoop stress8 hours minimum49 CFR 192.505(a)(4)
ASME SEC VIII Div.1Unfired pressure vessels1.3 x MAWP x (SA_test/SA_design)Must not cause visible distortion30 min minimum at full test pressureOSHA 29 CFR 1910.106

Source: ASME B31.3-2022 Section 345.4.2; ASME B31.4-2019 Section 437; ASME B31.8-2022 Section 841.4; 49 CFR Part 192 Subpart J; 49 CFR Part 195 (PHMSA 2025 updated versions).

Three US Pipeline and Piping Hydrotest Scenarios with Full Pressure Calculations

Representative hydrotest calculations from US onshore oil and gas operations, covering each of the three most common code applications in the field.

Gulf Coast, TX – B31.3 Refinery

Process Piping at Port Arthur Refinery: Temperature-Corrected Hydrotest

A carbon steel process piping system at a Gulf Coast refinery operates at 750 psig design pressure and 500 degrees F. At 500 degrees F, the allowable stress S is 17,000 psi. At ambient test temperature of 70 degrees F, the allowable stress ST is 20,000 psi. The B31.3 stress ratio is 20,000 divided by 17,000 equals 1.176, which is below the 6.5 cap.

Design pressure750 psig
CodeASME B31.3
ST/S ratio1.176
Multiplier applied1.5 x 1.176 = 1.764
Min test pressure1,323 psig
Hold time10 min minimum
Permian Basin, TX – B31.8 Class 2

Natural Gas Transmission Pipeline: Location Class 2 Urban Expansion

An operator expands a 16-inch NPS natural gas transmission pipeline through a Class 2 suburban area of Midland County, Texas. The pipeline is API 5L Grade X65 with 0.375-inch wall thickness. MAOP is 1,000 psig. Under ASME B31.8 and 49 CFR 192.505, Class 2 requires a 1.25 times test multiplier and 8 hours minimum hold time.

MAOP1,000 psig
CodeASME B31.8 / 49 CFR 192
Location classClass 2 (1.25x)
Min test pressure1,250 psig
Hoop stress26,667 psi (41% of SMYS)
Hold time8 hours minimum
North Dakota – B31.4 Crude Oil

Bakken Crude Oil Pipeline: Liquid Line Hydrotest under B31.4

A crude oil gathering and transmission pipeline in Williams County, North Dakota, operating under ASME B31.4 and 49 CFR Part 195. The 10-inch NPS API 5L Grade X52 pipeline operates at an MAOP of 800 psig. The system has 75 feet of elevation change from the test point to the low point, adding a head correction of 32.5 psi at the low point.

MAOP800 psig
CodeASME B31.4 / 49 CFR 195
Multiplier1.25x
Min test pressure1,000 psig
Low-point pressure1,032.5 psig (add 32.5 psi)
Hold time4 hours minimum

Six Expert Tips for Safe and Code-Compliant Hydrostatic Pressure Testing

1

Never Confuse Design Pressure with MAOP When Selecting Your Multiplier

ASME B31.3 uses design pressure as the base for the test calculation. ASME B31.4 and B31.8 use Maximum Allowable Operating Pressure (MAOP) as the base. These can be different numbers for the same system. MAOP is typically set lower than the design pressure to include a safety margin from the design factor. Using design pressure instead of MAOP for B31.8 will result in a test pressure that is higher than required, wasting water and time. Using MAOP instead of design pressure for B31.3 may result in a test pressure below code minimum. Know which number each code requires before picking up the calculator.

2

Always Check the Weakest Component in the Test Boundary

The minimum test pressure is set by the code based on the pipe or system design pressure. But the maximum test pressure is set by the weakest component inside the test boundary. Flanges, valves, instruments, and fittings may be rated lower than the pipe itself. A 1500-pound ANSI flange has a pressure rating of about 3,705 psig at ambient temperature for carbon steel. Testing a high-pressure system at 1.5 times design pressure could easily exceed valve body ratings or instrument connection limits. Always identify the lowest-rated component in the system before setting the target test pressure, and either remove it, isolate it with a blind, or reduce the test pressure to 1.1 times its rating.

3

Confirm Hoop Stress Does Not Exceed SMYS Before Starting the Test

For pipeline hydrotests under B31.8, the test pressure must not produce a hoop stress exceeding 100 percent of the specified minimum yield strength (SMYS) of the pipe. Operators running a test at 1.25 times MAOP on a pipeline near its design limit may push the hoop stress close to or above SMYS. Calculate: sigma equals PT times D divided by (2 times t). If the result is above the pipe SMYS, reduce the test pressure to stay below SMYS regardless of the code multiplier, and document the engineering justification. Overstressing a pipeline during a test can introduce work hardening that affects long-term fatigue life.

4

Account for Elevation Head at Every Low Point Before Setting Test Pressure

A gauge on the test pump shows you only the pressure at that point. Every foot of elevation below the test gauge adds 0.433 psi of additional water column pressure at the low point. For a pipeline dropping 200 feet, that is an extra 86.6 psi at the bottom. This can put fittings or valve bodies below the test header above their pressure ratings even while the gauge reads the target test pressure. Walk the line, identify all low points, calculate the head pressure at each one, and verify that every component at those low points is rated for the maximum possible pressure they will see during the test.

5

Monitor Pressure Continuously During the Hold Period for Temperature Effects

A falling pressure reading during the hold period does not always mean a leak. Water is slightly compressible, and temperature changes during the test also change pressure because water expands when it warms. A pipeline segment heated by sunlight during the test hold will show a pressure rise even with no pump input. Conversely, a segment cooled by wind or rain will show a pressure drop that looks like a leak. Before concluding that a pressure drop indicates a failure, check for temperature changes and account for them in your test log. Per ASME B31.4 Section 437, temperature recording is required during the hold period for this reason.

6

Document Everything for PHMSA and State Pipeline Safety Compliance

For pipelines under 49 CFR Part 192 (gas) or 49 CFR Part 195 (hazardous liquid), the test records are federal compliance documents that must be retained for the life of the pipeline. Per 49 CFR 192.517 and 49 CFR 195.310, test records must include the test medium used, test pressure applied, duration of the test, the equipment used to apply and monitor pressure, the name of the operator conducting the test, and the result of the test. Incomplete records are a violation subject to penalty. The PDF report from this calculator provides a compliant starting point for your test documentation package.

Quick Reference Table: ASME Hydrotest Pressure Requirements and US Federal Regulatory Citations

All four codes used in this calculator, with their minimum test pressure formulas, hold times, maximum limits, and the specific US federal regulation that enforces each one for pipeline operators.

CodeMin Test FormulaST/S or FactorHold TimeFederal RegulationPHMSA / Agency
B31.3 Section 345.4.21.5 x PD x (ST/S)Capped at 6.510 minOSHA 29 CFR 1910.119OSHA
B31.4 Section 4371.25 x MAOP1.25 fixed4 hours49 CFR 195.306PHMSA
B31.8 Sec. 841.4 Class 1-21.25 x MAOP1.258 hours49 CFR 192.505(a)(1-2)PHMSA
B31.8 Sec. 841.4 Class 3-41.40 x MAOP1.408 hours49 CFR 192.505(a)(3-4)PHMSA
SEC VIII Div.1 UG-991.3 x MAWP x (SA_t/SA_d)Per Appendix P30 minOSHA 29 CFR 1910.106OSHA

Sources: ASME standards current editions; 49 CFR Part 192 (updated July 2025); 49 CFR Part 195 (updated April 2024); phmsa.dot.gov. Verify current code editions before engineering decisions.

Hydrotest Pressure Calculation: Frequently Asked Questions

Answers for piping engineers, pipeline integrity specialists, plant inspection teams, and pipeline operators navigating ASME code requirements and PHMSA compliance.

The difference reflects the different safety philosophies and risk environments of the two codes. ASME B31.3 governs process piping inside plants and refineries where complex geometries, multiple branch connections, elevated temperatures, corrosive fluids, and frequent transient pressure events create greater uncertainty about stress concentrations. The higher 1.5 times multiplier provides a larger safety margin over the design pressure to prove out these complex systems. ASME B31.4 governs long-distance liquid pipeline transportation systems that are typically simpler in geometry (predominantly straight, welded pipe), engineered with extensive hydrotest data from decades of similar construction, and subject to more uniform quality control during manufacturing and construction. The 1.25 times multiplier was established by industry experience and PHMSA regulatory history as sufficient to identify weld defects and material flaws in those systems.
The temperature stress ratio, written as ST divided by S, accounts for the fact that steel is stronger at ambient test temperature than at the elevated design temperature. ST is the allowable stress of the pipe material at the test temperature (usually ambient), and S is the allowable stress at the design temperature (which can be elevated for high-temperature service). When a piping system operates at high temperature, its allowable stress S is reduced per ASME B31.3 Appendix A tables. Because the pipe is actually stronger at ambient temperature when tested, the code allows the minimum test pressure to be increased by this ratio. For a system with design temperature allowable stress of 17,000 psi and ambient test temperature allowable stress of 20,000 psi, the ratio is 20,000 over 17,000 equals 1.176, and the minimum test pressure is 1.5 times 1.176 times design pressure. The ratio cannot exceed 6.5 under any circumstances per B31.3 Section 345.4.2.
ASME B31.8 and the corresponding federal regulation at 49 CFR Part 192 classify pipeline locations by the number of buildings intended for human occupancy within a one-mile sliding window centered on the pipeline. Class 1 has fewer than 10 such buildings and represents rural, agricultural areas. Class 2 has 10 to 45 buildings, typically representing suburban areas. Class 3 has 46 to 100 buildings, representing urban areas. Class 4 has more than 100 buildings, representing dense urban centers. Classes 1 and 2 require a minimum test pressure of 1.25 times MAOP. Classes 3 and 4 require 1.40 times MAOP, reflecting the higher consequences of a failure in populated areas and the need for a larger proven safety margin. Per 49 CFR 192.611, if land use changes cause a pipeline to reclassify to a higher location class, the operator must confirm the MAOP is appropriate for the new class or reduce the MAOP.
For ASME B31.3, the maximum test pressure is limited by two criteria: first, the hoop stress in the pipe at test pressure must not exceed the yield strength of the pipe material at test temperature; second, the test pressure must not exceed 1.5 times the rated pressure of the weakest component (valve, flange, fitting) in the test boundary at the test temperature. For ASME B31.8, the maximum test pressure is governed by the hoop stress limit: the test pressure must not produce a hoop stress exceeding 100 percent of the pipe SMYS. Beyond these code limits, there is a practical upper limit on test pressure driven by the pump and equipment available for the test. Most field test contractors have equipment rated to about 10,000 to 15,000 psig maximum, but the engineering limits from the code always govern over equipment capability limits.
Pneumatic testing (using compressed gas instead of water) is allowed under ASME B31.3 Section 345.5 when the piping cannot be adequately dried after a hydrotest, or when the fluid handled is incompatible with water and residual water cannot be tolerated. However, pneumatic testing carries far higher risk than hydrostatic testing because gas is compressible and stores far more energy than water at the same pressure. A pipe rupture during a pneumatic test releases energy explosively, like a bomb, rather than the localized liquid jet of a hydrotest failure. For this reason, the pneumatic test pressure is only 1.1 times design pressure instead of 1.5 times, and all test boundaries must be cleared of personnel during pressure application. Under 49 CFR Part 192, gas pipelines must be hydrostatically tested unless PHMSA grants a specific waiver for pneumatic testing, which is rare for high-pressure transmission lines.
The hold time is the minimum duration that the test pressure must be maintained continuously without pumping additional water to compensate for pressure loss. During B31.3 process piping tests, the 10-minute minimum is for visual inspection of all joints, connections, and equipment inside the test boundary for signs of leakage. For B31.4 and B31.8 pipeline tests, the 4-hour and 8-hour minimums are not primarily for walking the line visually, but for monitoring the chart recorder pressure trace for any pressure drop that would indicate a slow leak or pipe failure. The pressure chart must show a stable, flat pressure trace throughout the hold period. Any unexplained pressure drop that cannot be accounted for by temperature change must be investigated before the test is declared a success. A passed test is a test where pressure holds at or above the minimum test pressure for the full required duration with no unexplained pressure loss.
Per ASME Section VIII Division 1 paragraph UG-99, the standard hydrostatic test pressure for an unfired pressure vessel is 1.3 times the Maximum Allowable Working Pressure (MAWP) multiplied by the ratio of the allowable stress at test temperature to the allowable stress at design temperature. This stress correction is similar to the B31.3 ST/S ratio. For most carbon steel vessels tested at ambient temperature and designed for ambient service, this simplifies to 1.3 times MAWP. For high-temperature vessels, the ratio increases the test pressure. The test pressure must be maintained for at least 30 minutes after the vessel reaches full test pressure. After the hold, all welds, connections, and penetrations are examined for leaks with the pressure reduced to MAWP or two-thirds of test pressure, whichever is lower.
Under 49 CFR 192.517 (gas pipelines), operators must retain test records for the useful life of the pipeline. Records must document: the date of the test; the name of the operator conducting the test; the test pressure applied; the test medium used; the duration of the test; the name and phone number of the responsible individual; and the results. Under 49 CFR 195.310 (hazardous liquid pipelines), similar record retention requirements apply. During PHMSA inspections, these records are among the first documents requested. Incomplete, missing, or falsified test records have been the basis for significant civil penalty actions by PHMSA, with penalties that can reach $266,015 per violation per day under 49 USC 60122 (as adjusted for inflation, 2024 figure). These records must be producible immediately upon PHMSA request.
According to the Bureau of Transportation Statistics and PHMSA 2024 annual report data, the US pipeline network includes approximately 300,000 miles of gas transmission and gathering pipeline, 195,000 miles of hazardous liquid pipeline, and over 1.3 million miles of gas distribution pipeline. All of these systems require initial pressure testing before entering service and retesting after significant repairs or modifications. Gas transmission pipelines in high-consequence areas also face periodic reassessment requirements under the Integrity Management Program rules at 49 CFR 192.903 through 192.967. PHMSA estimates that more than 25,000 miles of gas transmission pipeline are in or near high-consequence areas requiring integrity verification on a 7-year reassessment cycle.
A failure during a hydrotest, while dangerous, is the best possible time for a pipe or weld to fail because the test medium is water rather than natural gas or crude oil, and the energy release is far lower than a failure in service. When a hydrotest failure occurs, the sequence is: immediately stop pumping, vent test pressure safely, identify the failure location, document everything with photographs and pressure chart records, determine the failure cause through visual examination or destructive testing of the failed section, repair or replace the failed component, and retest the entire system from the beginning of the hold period. Any weld defect or material imperfection that causes a hydrotest failure would have caused a much more severe in-service failure if the test had not caught it. This is precisely why hydrotesting is required before commissioning under all four codes covered in this calculator.
These three terms refer to tests of increasing rigor. A service test or operational pressure test is simply operating the system at its normal operating pressure and checking for leaks, with no overpressure applied. A leak test under ASME B31.3 Section 345.7 is a separate, less rigorous test conducted at 100 percent of design pressure as a check for tightness, but it is not a substitute for the structural proof test. The hydrostatic pressure test is the structural integrity test conducted at 1.5 times or higher above design pressure to prove the pipe and all its joints and fittings can safely contain the design pressure with a demonstrated safety margin. Under 49 CFR Part 192, the hydrostatic test is the mandatory baseline for establishing MAOP, and cannot be substituted by a service test or leak test for new pipeline construction.
Water is the preferred medium for three reasons: safety, compressibility, and cost. Unlike compressed gas, water is essentially incompressible, which means a pipe failure during a hydrotest releases only a small amount of energy localized to the failure point rather than the catastrophic explosive energy release of a pneumatic failure. This is why pipeline test sites are safe to occupy during a hydrotest but must be evacuated during a pneumatic test. Water is also cheap and widely available for fill volumes ranging from thousands to millions of gallons for large pipeline segments. Practically speaking, the main challenge with water as a test medium is the need for proper disposal or discharge of the test water afterward, particularly for long segments in environmentally sensitive areas. Some operators treat and dispose of test water as regulated wastewater under state environmental permits.
Tie-in sections (short sections of pipe welded to connect a new pipeline to an existing operating system) present a unique challenge because they cannot be pressure-tested after being welded into the operating pipeline without taking the existing system out of service. ASME B31.8 Section 841.4 and ASME B31.3 Section 345.1 provide specific allowances for tie-in sections: each individual joint weld in the tie-in must be 100 percent radiographically or ultrasonically examined in lieu of pressure testing, and the adjacent sections of piping on both sides must be verified to have passed their required hydrotests. This examination-in-lieu approach requires documented approval in the quality plan and can only use NDT methods that have been validated against the material grade and wall thickness of the tie-in. This is why tie-in weld inspection is one of the most tightly controlled activities on any pipeline construction project.
A spike hydrotest is a special type of integrity verification test for existing gas transmission pipelines already in service. It is one of the reassessment options under 49 CFR 192.913 for the Integrity Management Program. In a spike test, the pipeline is pressurized to 1.25 times MAOP (the baseline test pressure) for 8 hours, and within the first 2 hours of that window, the pressure is briefly spiked to a higher level, typically 1.5 times MAOP, to expose fatigue cracks or stress corrosion cracking defects that might not fail during sustained overpressure but would fail under the spike. The spike duration is typically 1 to 2 minutes. The technical basis for the spike test is that the brief high-pressure excursion subjects any existing cracks to fracture mechanics stress intensity sufficient to grow or arrest them, while the sustained 8-hour baseline test catches slower leakers. PHMSA began accepting spike tests as a validated reassessment method in the 2019 Gas Mega Rule.
ASME B31.3 requires that the test gauge range be between 1.5 times and 4 times the test pressure. This means for a test pressure of 1,000 psig, the gauge range should be between 1,500 psig and 4,000 psig. A gauge too close to its maximum range has poor accuracy; a gauge far too large has poor resolution for detecting small pressure drops. The gauge must be calibrated and within its calibration period at the time of the test. Most operators use NIST-traceable calibration certificates valid within 6 months or 1 year of the test. For pipeline tests per 49 CFR Parts 192 and 195, a pressure chart recorder (deadweight tester or electronic data logger) is required to provide a continuous record of test pressure versus time throughout the hold period. Hand-reading a gauge is not sufficient for regulatory compliance on these tests.
Under ASME B31.8, a strength test (the main hydrotest or pneumatic test at 1.25 to 1.4 times MAOP) proves structural integrity and establishes the MAOP of the pipeline. A leak test, conducted at a lower pressure (at or near MAOP), confirms tightness but does not establish a proven safety margin above MAOP. For all new gas transmission pipelines operating at or above 30 percent of SMYS in Class locations 1 through 4, a strength test is mandatory and a leak test alone is not acceptable to establish MAOP. Some low-pressure gas distribution systems operating below 30 percent SMYS can use a leak test in certain circumstances per B31.8 Section 847. However, for any pipeline that would be subject to the integrity management requirements of 49 CFR 192 Subpart O, only a strength test provides the level of proof that PHMSA accepts for MAOP validation and reassessment purposes.