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SSC Test

SOHIC开裂检测 Test Item

Sulfide Stress Cracking, SSC

Test Purpose

Examine the Resistance Property of Material to SSC

Test Object

Petroleum Pipeline, Boiler, Liquid Gas Storage Tank and other Pressure Vessels, metal products

 

 

 Project Introduction

 Te

      Sulfide stress cracking (SSC) or sulfide stress corrosion cracking (SSCC) is a special type of stress corrosion cracking (SCC), but is different from common SCC。 The main role of environment in the common SCC is anodic dissolution, while the main role of environment in SSC is cathodic hydrogen charging。 The SSC mechanism has not yet been fully revealed。 But at the moment, most scholars tend to that the cracking is caused by hydrogen, and sulfur ions or hydrogen sulfide have a certain role in promoting the diffusion of hydrogen into the materials。

      In the transmission pipelines of petroleum and natural gas (especially natural gas), SSC of high pressure & high strength pipelines will lead to major safety accidents, so need to evaluate the resistance to SSC for pipeline steel, ensure the safety of the pipeline.

       Relate test:Hydrogen induced cracking                                                                   Application form:Download

 

 

 Test method and standard

Test Method

Test Standard

Sample Requirement

Remark

Method A—Tensile Test

NACE TM0177-2005,

GB/T 4157-2006,

ASTM G39-99,

ISO 7539-2011,

Simulated test of working condition

Additional blueprint

Temperature: 25±3℃;

Loaded Stress: 80% yield strength;

Test Medium:

Solution A: NaCl 5%, acetic acid 0.5%, solution saturated by H2S;

Solution B: NaCl 5%, acetic acid 0.23%, sodium acetate 0.4%, solution saturated by H2S;

 

Method B—Bent-Beam Test

American standard (Three-Point Bend):

67.3mm*4.57mm*1.52mm.

Chinese standard (Two-Point Bend): 110-255mm long by 15-25mm wide. 0.8-1.8mm thickness for specimens need be loaded big strength (200MPa)

Method C—C-Ring Test

American standard: Outer diameter ≥15.9mm;Chinese standard : Outer diameter ≥15mm. Specific sizes refer to the drawings

Method D—DCB Test

American and Chinese standards: 110mm*30mm*10mm

Four-Point Bend

110-250mm long by 15-50mm wide, thickness is supplied by client。

Galvanically Induced Hydrogen Stress Cracking (GHSC)

NACE TM0177-2005

Refer to the conditions of H2S test

GHSC test shall be carried out according to the above requirements of the SSC test, and meet the following additional requirements, options and instructions.

a) CRA specimens form a thermocouple with unalloy steel (carbon steel) immersed fully in test solution. The ratio of the area of unalloy steel to the submersed area of CRA specimen shall be 0.5~1 according to NACE TM 0177-1996. Stressing jig shall be insulated with specimens and coupled carbon steel. For assessment of specific application, CRA can coupled with low alloy material which will be coupled with CRA in use and is in use.

b) Test environment is solution A of NACE TM0177-1996, partial pressure of H2S is 0。1MPa, and the temperature is 24℃±3℃。 For assessment of specific application, the SSC test environment described in Clause 2。5 of Appendix E can be used。

 

 Test equipment:Stress Ring

       Our lab is strength, and there are enough stress rings to perform 120 groups of SSC tests and 200 groups of HIC tests at the same time.

硫化氢应力腐蚀应力环

   Sample requirements

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