Gray Iron. 4

[Frank1344]

Gentlemen,

Can you please kindly advice me about differences between SA48 and SA278?

Our case is about a Compressor casing. We want to know which one is a right choice?

Is also corrosion an issue to consider any of them?

With Kind Regards,
Frank
Calgary, Alberta

 

[metengr]

Frank1344;
There is no SA 48 under ASME B&PV Code material specification requirements. There is an ASTM A 48,titled Standard Specification for Gray Iron Castings(these are castings for general use), and there is an ASME SA 278 titled, Specification for Grey Iron Castings for Pressure-containing Parts up to 650 deg F. The castings are classified based on Class No related to minimum tensile strength.

Are you sure this compressor casing is not cast carbon steel? Are you reverse engineering an existing case or designing a new case? If this is a new case and is pressure containing, I would carefully evaluate either cast carbon steel or ASME SA-278, and select the appropriate strength level.

 

[Frank1344]

Thank you for the feedback.
We are looking to buy a compressor for a temporary Vapor Recovery Unit (VRU), the Vendor has a couple of compressors off the shelf with A48 material.
All the codes and guidelines are also in acceptance with your comments.
we are just wondering if it is for a short remedy, this material can work till the proper engineering is going to be in place.

Regards,
Frank

 

[metengr]

Frank1344;
I would verify the operating conditions with the vendor to make sure the temporary compressor would be acceptable. The concern to me would be operating pressure and temperature, and making sure the A 48 material can handle these conditions.

 

[deanc]

http://www.foundry.elkem.com/hits/i...u?readform&id=foundryeng&full=full&lo=konsern

Best Cast Iron site I have ever found.

As metengr states I would study this for the application. Check out the site and look up your ASTM specs.

 

[arunmrao]

I visited a compressor manufacturing unit today and observed that the casing was cast iron material. However these were small air compressors. The path for the cooling water to flow were all as cast.

However given a choice, cast steel will be a preferred material.

 

[EdStainless]

I had only seen a few of these, and they were ductile iron.
Unless these are very small and bulit with huge safety factors I would be leary of gray iron in a pressure containing application.

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