What is lowest MDMT of SA-266 Gr.2 & SA-106 Gr.B?
What is lowest MDMT of SA-266 Gr.2 & SA-106 Gr.B?
(OP)
Dear Sir,
Two questions:
1. SA-106 Gr.B has been requested (by client) for an MDMT of -28°C. And it got charpy tested at -28°C and failed. Is SA-106 Gr.B not suitable at -28°C?
2. Can SA-266 Gr.2 be used at -29°C? What's the lowest temperature it can pass during charpy V-notch testing?
Please share if anyone has experience.
Thanks.
Two questions:
1. SA-106 Gr.B has been requested (by client) for an MDMT of -28°C. And it got charpy tested at -28°C and failed. Is SA-106 Gr.B not suitable at -28°C?
2. Can SA-266 Gr.2 be used at -29°C? What's the lowest temperature it can pass during charpy V-notch testing?
Please share if anyone has experience.
Thanks.





RE: What is lowest MDMT of SA-266 Gr.2 & SA-106 Gr.B?
SA-106 Grade B material is most suitable for elevated temperature service (review the material specification scope). Hot finished pipe material could be supplied with no supplemental heat treatment but rest assured will have a coarse grain size that translates to much lower notch toughness. Notch toughness is not a requirement for this material.
If a normalize and temper heat treatment were specified, the material should be acceptable at -28 deg C. However, why not select an alternate pipe material?
RE: What is lowest MDMT of SA-266 Gr.2 & SA-106 Gr.B?
Yes, despite the higher carbon content this material can be acceptable for use at -29 deg C MDMT because it can be specified as normalized and tempered or quenched and tempered.
RE: What is lowest MDMT of SA-266 Gr.2 & SA-106 Gr.B?
Re SA-106 Gr.B, this material has been selected and procured based on client's material selection report (which allows SA-106 Gr.B above -29°C). But it failed during impact testing (reported at 10J avg against 27J min.).
Now we've decided to go with SA-333 Gr.6 which we normally specify for temp. below -29°C.
Again, thanks your advice.