Tests

A tension test applies a load to the test section until it ruptures. The yield strength is the stress at which plastic elongation of the stress piece takes place.

UT

Ultrasonic or UT testing of a steel plate uses UT test equipment to examine the plate looking for internal discontinuities. Depending on the acceptance class and plate thickness of the UT test the maximum size of discontinuities is a 75mm diameter circle when ASTM A578 is used as the test standard. Oakley Steel tests to level C “Any area where one or more discontinuities produce a continuous total loss of back reflection accompanied by continuous indications on the same plane that cannot be encompassed within a 1–in. [25–mm] diameter circle is unacceptable.” (ASTM A578 s9.1).

Charpy V-Notch Impact

Test Temperature °F by Thickness
Grade≤ 25mm> 25mm and ≤ 50mm> 50mm and ≤ 75mm> 25mm and ≤ 125mm
ASTM A516 Gr. 60– 60– 50– 50  50
ASTM A516 Gr. 65– 60– 50– 40– 25
ASTM A516 Gr. 70– 50– 40– 30– 20

HIC

The HIC test can be performed in accordance with EN10229 or NACE TM0284. For both standards the test can be done using either Test Solution A, or Test Solution B. The difference between the test solutions is that Solution A has a pH of 3 whilst Solution B has a pH of 5.

For pressure vessel plates being tested under TM 0284 a several 10cm by 2cm by plate thickness samples are placed in the test solution and H²S is then bubbled through it for 96 hours.

After the test is completed the samples are sectioned and polished so that any cracks can be easily distinguished. All the cracks that can be detected at up to 100 times magnification are then measured. The results are then analysed and the test results are provided in the CSR – crack sensitivity ratio, the CLR – crack length ratio and the CTR – crack thickness ratio.

The value of the ratios then indicates what acceptance class the plate can be sold as.

SSC

Steels and weldments with a high hardness are more susceptible to sulphide stress cracking. To reduce this susceptibility steels with a low hardness are used and this is tested with a hardness test. Using the Rockwell HRC test on carbon steel plate the maximum permitted value is 22HRC.

Hardness Testing

Hardness testing determines the ability of the plate to resist penetration. There are two tests commonly used to determine hardness; Brinell and Rockwell. In the Brinell Test a ball is fired at the plate and the diameter of the indentation in the plate measured.

Through

Through testing tests the tensile strength of the steel plate in the direction perpendicular to the one in which it was rolled. In other words it is the tensile strength through the thickness of the plate rather than its length. Through testing helps to detect plates that would be susceptible to lamellar tearing and is described in detail in ASTM A770.