Bolts for cryogenic application 4

[afocuf]

Hiya,

I'm looking for an alternative to ASTM A193 Grade B8 Class2 material. According to ASTM A193-05 (page 88, bottom of table), the diameter is limited to 1 1/2in., whereas larger diameter bolts are required for the particular application I'm looking at.

Is my interpretation of the code correct? If so, can you guys suggest an alternative material which matches the strength and corrosion resistance of B8 Class2 (eg Ni-alloy 625)?

Any thoughts on this would help, thanks.

 

[mcguire]

A-286 should cost a lot less and give you better properties.
I don't know what the code permits, but this iron based superalloy, originally designed for high temp use, would have good cryogenic properties since it's also austenitic.
Check

http://www.alleghenyludlum.com/ludlum/Documents/al286 (053106).pdf.

Cold-worked 201 or a nitronic might also work.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[CoryPad]

You should be using ASTM A 320 Standard Specification for Alloy/Steel Bolting Materials for Low-Temperature Service. It also has grade B8 Class 2.

The standards don't exclude making parts larger than 1.5 inches. Just contact some good suppliers and see if they can provide larger diameter parts that meet your requirements.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[TVP]

As the knowledgeable mcguire pointed out, A-286 is one of the grades that has been used successfully in cryogenic applications when higher strength is needed. Alloy 718 is the other high strength grade typical for these applications. Both are listed in ASTM F 2281 Stainless Steel and Nickel Alloy Bolts, Hex Cap Screws, and
Studs, for Heat Resistance and High Temperature
Applications because there is no real low-temperature bolt specification other than ASTM A 320.

To answer your other question, yes, ASTM A 193 limits the diameter for Grade 2 fasteners to 1.5 inches max. Grades 2B and 2C are available with similar strength to Grade 2 in larger diameters.

 

[metengr]

afocuf;
Just curious, what your application is for cryogenic bolting? As mentioned above, you may be indeed be limited by construction code requirements. If this is the case, I would caution you that the A 320 bolting material specification mentioned by CoryPad is what you need.

 

[afocuf]

Metengr,

I'm afraid I don't know much about the application all I know is that LNG is involved (storage tanks, I presume).

Cheers,

 

[mcguire]

These tanks are usually 9% Nickel or the less expensive 201 or 201LN.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[metengr]

afocuf;
Do NOT use A 286 bolting material. Use A 320 bolting materials, these are endorsed by ASME Codes and Standards for this type of application. Thanks for the added information.