Third party SSC test
Contact: Mr. Wang cell phone: 13102238283 (WeChat with)
Tel: QQ:3144667033 022-23892103
SCC: stress corrosion cracking corrosion cracking stress. In the presence of water and H2S, with the local corrosion of the anode process and tensile stress related to a metal cracking, stress corrosion and corrosion of the metal caused by the synergistic effect of the phenomenon (see metal corrosion). It has three main features: 1 stress corrosion cracking is a function of time. The larger the tensile stress, the shorter the time required for the fracture, the stress of the fracture is generally lower than the yield strength of the material. This stress includes the stress, residual stress and the wedge stress of the corrosion product, which is produced by the external load. 2 corrosive medium is specific, only some of the metal medium combination of the case, the stress corrosion cracking occurs. In the absence of stress, the corrosion rate of the metal in its specific corrosion medium is small. 3 the fracture velocity is between pure corrosion and mechanical damage, and the fracture is brittle fracture. SSC test standard
TM 0177-2016 NACE: metal in the H2S environment, the resistance to sulfide stress cracking and stress corrosion.
MR 0175-2009 NACE: General principles for selection of materials used in petroleum and natural gas production in the use of hydrogen sulfide (H2S) in the environment of oil and gas.
GB/T4157-2006: metal in hydrogen sulfide environment in the special form of environmental cracking laboratory test.
15156-1-2009 ISO: General principles for selection of materials used in petroleum and natural gas production in the use of hydrogen sulfide (H2S) in the environment of oil and gas.
0599-2006 SY/T: metal material requirements for resistance to sulfide stress cracking and stress corrosion cracking of natural gas ground installations.
Microscopic map after SSC test
SSC hydrogen sulfide stress corrosion conditions:
(1) corrosion environment:
1 medium containing liquid phase water and H 2 S, and the higher the concentration of H 2 S, stress corrosion caused by the rupture of the more likely to occur.
2 only occur in acidic solution, pH is less than 6 are prone to stress corrosion cracking; pH is greater than 6, the formation of iron sulfide and iron sulfide film to protect the good performance, not prone to stress corrosion cracking. When cyanide ions exist in the system, the cyanide ions combine with the ferrous ion to form a complex ion, which is much smaller than that of FeS, so the FeS has lost the film formation condition, which causes the stress corrosion cracking of the system.
3 the corrosion environment temperature is 0 ~ 65.
(2) the structure of the material (the shell and its welds, take over, etc.) must exist stress.
(3) the corrosion environment of the materials with the same corrosion, such as the H 2 S under wet conditions on the stress corrosion of high strength steel