ENERGY

Hydrogen Pipeline Material Testing 

Facility 

Objective

We provide critical data, measurement methods and models that enable safe 

and economical transport, delivery and storage of hydrogen fuel, an abundant, clean-burning alternative to conventional fossil fuels. Currently, we are 

generating fatigue data for pipeline materials including steel alloys currently 

being used (API X52), those proposed for use (newer versions of X52 as well 

as X65 and X70), and older pipelines made of X52 to X70 materials that might 

be repurposed. Using this data, we can model the performance of pipeline 

materials and make predictions about the safe operating limits of pipelines 

carrying pressurized gaseous hydrogen, thereby helping to inform and revise 

relevant codes and standards.

Impact and Customers

While pipelines are the safest, most economical way to transport fuels, the parameters used for codes and standards for the transport of hydrogen are based 

on tensile test data that is over 30 years old. In order to enable the design of safe 

pipelines and the use of hydrogen as an alternative fuel, a working understanding 

of the relationship between fatigue performance of pipeline steels and hydrogen 

gas pressure and loading parameters is needed. 

Since pipelines operate at low loading frequencies, fatigue data takes a very long 

time to produce. NIST has developed a measurement system that reduces this 

time by a factor of 10.

Critical data from this project directly informs codes from ASME and CSA America.

Customers impacted by this work include ASME, CSA America, Evraz, Air Liquide, 

Praxair, El Paso, PG&E and others.

Based on 2011-2012 cost numbers from industry, use of X70 steel rather than X52 

steel would result in a savings of over $1 million per mile of pipeline.

Approach

NIST has a unique capability for measuring mechanical properties of structural materials in pressurized gases. Our primary focus is fatigue measurements in high-pressure hydrogen gas, but our capability is applicable to all high-pressure gas environments. We use two 

load frames, each outfitted with a high-pressure chamber for mechanical measurements. One chamber can test a single specimen in a 

gas atmosphere at up to 140 MPa, and the other can test up to 10 specimens simultaneously in up to 38 MPa gas. The measurements 

are remotely and automatically operated for safety, reliability and repeatability. 

We test modern pipeline steels such as X52, which have low carbon for weldability and predominantly acicular ferrite microstructures. 

Because higher-strength alloys such as X70 would permit future pipeline designs to be even more economical, we are testing those as 

well. An efficient way to transport hydrogen could be achieved by re-purposing existing pipelines, so we are also measuring the fatigue 

properties of older alloys. Older alloys have different microstructures and different chemistries, and therefore may behave differently in 

hydrogen. While our focus has been on base materials, we will soon begin a systematic matrix of tests on seam and girth welds, including the weld itself and the heat-affected zone, from both old and new pipelines.

We have developed a model that uses the fatigue data and pipeline design inputs to predict the lifetime of a hydrogen pipeline. The 

model can predict fatigue crack growth rate as a function of operating pressure and load frequency, and can account for different microstructures. Estimates of lifetimes can be output as a function of existing flaw size. 

Industry members of the ASME B31.12 Committee on Hydrogen Piping and Pipelines have given us guidance on which materials to test 

and continue to guide us on the priorities for the modeling effort. The data from this project are being used by the committee to modify 

the code; prior to this work there was no information on fatigue crack growth of pipeline steels in hydrogen gas.
ENERGY

Our group has developed a test method 

that simultaneously measures 10 specimens 

at once, maintaining specific environmental 

and loading conditions until all 10 specimens have completed testing. Pipelines run 

at very low loading frequency, which generally increases their lifetime, expressed as 

the number of cycles until failure. However, 

with hydrogen, low loading frequency is 

an issue because the time per cycle is long 

enough for hydrogen to completely diffuse 

to a crack tip where damage per loading 

cycle is maximized. Therefore, testing of fatigue in these conditions requires low loading frequencies and long times. Before we 

invented our test methodology, it took too 

long to determine a set of critical data large 

enough to be of use to the industry. The 

unique NIST design allows the test to continue until all 10 specimens are measured 

before opening the test chamber, minimizing testing time.

Two load frames, each with a high-pressure 

test chamber, can be run simultaneously 

and at different hydrogen (or other gas) 

pressures. The plumbing for gas supply was 

designed and built to operate in a fail-safe 

manner, so that—upon loss of power, air 

pressure or ventilation—numerous interlocks prevent further 

gas supply to the laboratory. 

Additionally, hydrogen sensors 

monitor the laboratory for leaks. 

A program was developed to 

automate the gas supply and 

pressure maintenance of the two 

high-pressure test chambers. 

This program also monitors all 

power and safety systems so 

that the gas supply system can 

be shut off in an orderly manner upon sensing one of the interlocks. An additional program 

was developed to allow remote 

monitoring of the system. This 

program also sends automatic 

text messages to members of the team if 

any critical error is encountered by the system, such as a hydrogen alarm, loss of compressed air or loss of laboratory ventilation.

We have measured fatigue crack growth 

rate on over 70 specimens, including six 

steel alloys. Each set of 10 specimens 

that we simultaneously test includes both 

sample seam and girth welds. This data is 

regularly presented to the ASME B31.12 

committee. This data has allowed 

us to quantify the effects of gas 

pressure and loading frequency on the rate of fatigue crack 

growth. We have observed differences in fatigue crack growth 

rate between newer, acicular ferrite and older ferrite/pearlite microstructures. 

We have developed a phenomenological model of fatigue crack 

growth rate as a function of hydrogen gas pressure and load 

frequency and constitutive relations have been added that provide a predictive capacity. Figure 

1 is a preliminary application to 

a new X52 alloy. We have done a 

parametric sensitivity analysis that will aid 

real-life pipeline design. Parameters that 

pipeline operators would use, such as pipe 

wall thickness, operating pressure, pressure ratio and loading frequency are used 

as inputs and lifetime in the form of number 

of cycles to failure is given as the output. 

Figure 2 shows a representative sensitivity analysis of initial crack size, generally 

defined as the limit of a detectable crack. 

Different types and geometries of cracks 

result in different initial flaw size, and the 

model can account for crack size, as well as 

crack geometry.

NIST has worked with industry partners from 

the ASME B31.12 Committee on Hydrogen 

Piping and Pipelines and CSA America task 

group on compressed hydrogen materials 

compatibility to develop a matrix of tests 

that includes different strengths of alloys 

and varying ages and microstructures. The 

first few years of work has focused on measurement of base metals, while future work 

will focus on seam and girth welds, once 

again measuring material from alloys of 

varying strength, age and microstructure.

Learn More

Elizabeth Drexler, Robert Amaro, 

Damian Lauria, Neha Rustagi and 

Kati Eason

Andrew Slifka, Materials Research 

Engineer

303-497-3744

andrew.slifka@nist.gov

http://www.nist.gov/mml/acmd

Publications

NE Nanninga, AJ Slifka, YS Levy, and C White, A review of fatigue crack growth for pipeline steels 

exposed to hydrogen, J. Res. NIST, 115 (6) 437-452 (2010).

NE Nanninga, YS Levy; ES Drexler, RT Condon, AE Stevenson, AJ Slifka, Comparison of hydrogen 

embrittlement in three pipeline steels in high pressure gaseous hydrogen environments, Corrosion 

Science, 59 1-9 (June 2012).

Accomplishments

Figure 1. Data for X52 and model prediction for a representative measurement of X52 at 34MPa hydrogen gas and 1 Hz loading frequency 

at R=0.5

37_nrg-12/12

Figure 2. Lifetime prediction generated from the model as a function of 

initial crack length, based on representative fatigue crack growth data