High Pressure High Temperature Bolting

[pingmi]

Hello,

I need to select suitable bolting material for bonnet studs / Nuts of a High Pressure valve. Following are the specification:

Valve body / Bonnet material : ASTM A182 Grade F91
Body design Condition: Class 2500
Maximum Operating pressure: 220 barg
Maximum Working temperature: 610°C
Application: Condensate, Steam

I need to know if it is okay to use UNS N07718 (ASTM B637) bolting with F91 valve body at the specified design conditions. Would there be any issues like galling, galvanic corrosion etc.

Do we have any other high strength bolting material options for use with F91 valve bodies?

Thanks in advance.

 

[XL83NL]

See this thread a similar topic, and bolt material suggestions. I believe ASTM B637 UNS N07718 provides the highest allowable stress value per ASME II-D.
Not sure on galling issues, you may find this topic useful.

Whats your design code?

 

[pingmi]

Thanks XL83NL for your response.
To answer your query on design code: Since these valves are integral to trap module,the applicable design codes are ASME B31.1 / ASME SEC VIII div I.

 

[alby87]

A possible solution is A193 gr B16 and A194 gr 4. Those materials are good with high temperature (around 550°C) and high pressure.

 

[pingmi]

Alby87,

A193 Gr B16 / A194 gr 4 bolting combination has much lower strength values at high temperatures as compared to ASTM B637; which results in higher bolt diameters for the same application. Hence I'm more interested in ASTM B637.

Thanks.