ACME thread gauges

[Gopher64]

I work in the Propane industry and we use ACME threads as connectors for our transfer hoses. We have recently had a connection fail under pressure due to wear on both the male and female parts of the coupling. The ACME couplings have threads made as either 2.25x6-ACME-2G or 3.25x6-ACME-2G. We want to get No Go gauges to test both the male and female sides of the couplings (so, a total of four No Go gauges) so that we can ascertain when they've reached a reasonable amount of wear and need replacing.
My question is what is a reasonable amount of wear and how do I specify that to a precision toolmaker so he can make me some gauges?
I know that it is probably easiest to just visually inspect them, but we have a large number of sites and the local guys don't really know what they're looking for.

Gopher

 

[unclesyd]

I would get with the coupling maker and discuss your needs as to gauging the threads in his couplings. Normally they are very accommodating especially concerning their connector. He will also be able to point you to any regulations that pertain to your product, as I think all LG tanks/valves have to have some type approval. The regulations should give some guidelines as to gauging.

 

[unclesyd]

Try these people as a starter for the gauges.
I still would talk to the coupling manufacturer about the problem. I know he doesn’t want his coupling involved in a failure anymore than you want a failure.

http://www.gaging.com/

 

[Gopher64]

Thanks,
I am trying to get some sense out of the manufacturer but they are in the US and I'm in Australia. A resounding silence is all I've got so far, which is why I tried posting this query.
Generally speaking, everything in the LPG industry is UL approved.
As far as I can find, ACME threads are covered by the American Standard B1.5-1952. I have a copy of the relevant part of this standard and it tells you all about how to make a new thread. However, it does not say how much wear should be allowed on a used one.

 

[Iskit4iam]

If I were the manufacturer I wouldn't allow any wear. It the thread goes outside the normal tolerances I'd say the coupling was unsafe. That might not be practical but I bet that's why they've been silent. They may never have considered the consequences of worn threads.

 

[Gopher64]

To those of you who have considered this question, thanks. I have been pointed in the direction of a manufacturer in the UK who supplies ACME thread wear gauges for the LP Gas industry. Re-Manufacturing Services (

http://www.rmsgaseng.com)

supply them. We've purchased a set and have been very happy with them. Have a look at the web site. They explain it there.
Thanks

 

[unclesyd]

Appreciate the follow up reply on the resolution of your problem. Your information will be of help to someone in the future.
It's commendable on your part wanting to ensure that the connecters are functional and safe.