"ASTM A193 Gr B7" Hydrochloric acid service

[shahyar]

Hi,
On a FRP tank for Hydrochloric acid 32% in ambient temperature, we proposed Hastelloy, but vendor says:"ASTM A193 Gr B7" for stud bolts. Which is better material?
(Outdoor tank, min Amb. Temp = minus 45 deg C)

Regards

 

[Metalguy]

Will the bolts be wet by the acid or fumes? If so, they won't be bolts for long-they're low-alloy steel like 4140. Which Hast. would be used?

 

[unclesyd]

B7 No; Hastelloy C Yes.
We also use a lot of Silicon Bronze in this service for flange bolting, especially in the smaller sizes.

 

[moltenmetal]

PTFE-coated B7 studs and 2H nuts are commonly used, temperature permitting. Forget about Hastelloy bolting- $$$ and galling tendency will both be enormous.

 

[shahyar]

Thanks. Your comment are very helpful.