1.5" NPT Pressure Rating 1

[Mchel80]

Hi,

I am trying to find the pressure rating of 1.5" NPT Threads. I have been looking at the net and I was able to find the rating for threads smaller than 1". I am using the 1.5" NPT at a temperature of 200 degree C. Can you assist me with finding the pressure rating and the derating factor for the temperature specified.

MChel

 

[BigInch]

Threads don't have a pressure rating. The piping components with the threads have the pressure rating and the skill of the plumber, combined with the thread sealing material he uses, are assumed to be adequate to contain the pressure specified by the rated pressure of the pipe component.

 

[Mchel80]

Hi BigInch,

I have been using NPT threads for a while and the NPT Connections have always come with some pressure rating. I have the below link with the pressure rating for the NPT threads. This goes upto 1" only.

http://www.sealexcel.com/tube-fittings.html

MChel

 

[blacksmith37]

There are hundreds threads available for oil field tubing and casing because 8round, aka NPS , does not RELIABLY hold pressure. ( And what pressure it holds , is a function of the dope used).

 

[BigInch]

Mch,

Your link shows compression fittings. The pressure retaining capacity of those have little to do with their threads. The bulk of the pressure is retained by brute force wedging of metal to metal faces against eachother. The threads simply provide the mechanical means of reaching the force necessary to do so.

 

[rconner]

I suspect this must to some extent also depend on the specific material(s), and maybe even the piping configurations involved (e.g. see

http://www.engineeringtoolbox.com/iron-threaded-fittings-d_855.html

and

http://www.alloystainless.com/elbows.htm

etc). [As to field performance, most traditional references note a great deal depends on the installer, and also that well-formed, clean threads and a good sealant he/she is working with are also helpful! I guess much weaker materials like plastics also have their own relatively unique set of issues, but I guess it is unlikely you are dealing with those at the temperature you’re talking about.]