Line blank material choice in 9Cr material specifications
Line blank material choice in 9Cr material specifications
(OP)
We have both 5Cr and 9Cr piping material specifications. ASME B16.48 (steel line blanks) only lists forged material for 5Cr, and no 9Cr material is listed. The forged material is listed i presume because forgings are less susceptible to laminations than plate material. What type of material should be chosen for 9Cr specs ? 9Cr forging, which is not listed in ASME B16.48 or should we go with 5Cr material which has less strength/corrosion resistance ?
Any input will be appreciated.
Any input will be appreciated.





RE: Line blank material choice in 9Cr material specifications
For a Disk & Donut blind, one thing you might want to ask is:
"Will this "blind" ever see the actual line operating conditions?"
Most plate blinds (Disk) are a shut down item and more of a safety item therefore does not come in contact with the commodity at the normal line pressure and temperature.
A lesser material may be acceptable here.
The ring spacer (Donut) however will see line conditions to a limited extent.
A line quality material would be required here.
RE: Line blank material choice in 9Cr material specifications
John
RE: Line blank material choice in 9Cr material specifications
9 Cr is selected for its superior resistance to corrosion and hydrogen embrittlement compared to 1 1/4 and 5 chrome in hydrogen rich service at elevated temperatures.
The stabilized stainless steel grades Type 321 & Type 347 are often specified as alternative materials in lieu of the 9 Cr. On many projects that I've worked on, the material is chosen based on availability, price and the delivery schedule. I've seen several systems with 9 Cr pipe and 347SS valves.
Bottom line - If you can't get 9 Cr Line Blanks, consider using 321SS or 347SS as an alternative. Be sure to get approval from your process engineer.
NozzleTwister
Houston, Texas
RE: Line blank material choice in 9Cr material specifications
John