Flange Rating for Compressor

[PAN]

I'm in doubt about the flange rating/facing for reciprocating compressor. After search the previous thread there is relevant thread.

900# FF flanges ?
thread378-70856

In my case, the 1st stage has pressure less than 70 barg. Therefore, the cylinder material will be cast iron as API 618. The preliminary data sheet shows flange Class 600 FF.

I check the cast iron flange rating in ANSI B16.1. There is no Class 600 FF. Should I specify Class 800 RF? If we consider about the connection to steel flange 600 RF or RTJ. Should we revise the data sheet?

Please comment.

 

[Montemayor]

PAN:

Don's make a fatal mistake by substituting your estimate for the actual, manufacturer's design value. All reciprocating manufacturer's have a documented MAWP rating on their cylinder castings - which is where this flange obviously is located. Go directly to the manufacturer of the compressor (or the "cylinder") and obtain their official rating (or MAWP) for the subject flange AT THE WORKING TEMPERATURE.

You will find them very cooperative - if they are still around. If the manufacturer is not around anymore, use an experienced, registered mechanical engineer to research and rate the subject flange - putting his professional "stamp" on the calculations. It is important to recognize that a complex industrial casting such as the one we are discussing is done using proprietary and arcace techniques that often are not known to many other engineers. The easiest and best safety procedure is to get this value from the manufacturer of record - and get it documented (as well as all their ratings on ALL the other flanges and cylinders involved in this compressor assembly. It is normal and expected practice for experienced and recognized manufacturers (like Dresser Ingersoll-Rand and others) to stamp their cylinders with the MAWP values of each using SS name plates. You need this critical information in ordert to set line "specs" on all your piping and fix PSV settings - as you are probably now finding out.

Good Luck.

 

[PAN]

Montemayor,

Thanks for your advice. I have asked the question to compressor manufacturers. Hope I can find the solution soon.