ISO Standard for Pipe Fittings - Min thread engagement

[miketurbo]

Hello,

I'm looking into the feasibility of of using a 3/4" or 1" ISO pipe fittings for an oil drain but having trouble locating information regarding the minimum thread engagement/depth for such a pipe.

Could someone please point me in the direction of where this information can be found or what the standard number is?

Thanks,

 

[XL83NL]

Good question, been asking myself the same for application of threaded joints in EN 13480 piping.
Either the design code you're design code dictates such requirements, or the thread standard itself (e.g. ISO 7-1) can you tell this info.

However, Ive noticed not all current editions of EN design codes (e.g. EN 13480) call out requirements as explicitly as e.g. ASME standards do.
On example Ive run into is the minimum required thread engagement for bolted flange joints acc. EN 13480.

 

[rconner]

A little more information might help perhaps in getting some more meaningful advice. You start out referring to " 3/4" or 1" ISO pipe fittings ", but then at the end say "such a pipe". Are you simply designing just a 3/4" or one inch threaded pipeline that involves these fittings that is not connected to anything else (and wondering if the threaded spigot ends are brought up proper/sufficient distance into the threaded sockets, are you thinking about tapping a larger (steel?)pipeline penetrated at these sizes e.g. at the very bottom for a drain mechanism for the larger line and wondering about the thread integrity at the penetration, or what?

 

[miketurbo]

Thanks for your responses. XL83NL I'll take a look into those standards today. rconner, I am investigated the use of both a 3/4" and 1" male pipe connector which would be threaded directly into a cast iron sump like part. The threaded connector is attached to a flexible pipe section.

I use the term 'such a pipe' as I assumed (maybe wrongly) that there are constant ratios for minimum thread engagement as there are when using bolts, and I was hoping to find such an equation or table.

 

[rconner]

Hmmm (sounds almost like some kind of "drip pot" like arrangement). While tapered pipe threads are definitely differnt than bolts, I think about a thousand years ago I know the Crane Company (and probably others) published a table of "Normal Engagement Between Male and Female Threads to Make Tight Joints". However, for probably obvious reasons it was provided with several caveats. I believe the normal engagement shown for 3/4" and 1" at least American Standard and API Line Pipe threads at the time was 9/16" and 11/16", respectively. Among the caveats were that type of piping material, fits, and actual cut or rolled thread conditions could affect this, as well as amount of wrenching effort required to obtain same (drawing attention particularly to threaded materials softer than steel).
I guess when you get into some types of stainless steel there might even be other caveats (such as galling, with and without "anti-seize etc.), and with anything cross-threaded all bets are off! Putting all this together in the modern world there may well be reluctance to publish this sort of info due to the many variables and liability concerns etc. (maybe why you are having trouble finding such?); however, I would think you could probably find some info at least helpful to your understanding by web-searching e.g. with "threaded pipe joints" or "normal thread engagement" etc. keywords.

 

[miketurbo]

I've done a bit more research and had a read of the 'machinery's handbook' and have come across the same numbers as you mention. This is exactly the kind of figure I'm looking for, for this preliminary groundwork but I can't seen to find anything relating to BSP/ISO.

I've read that there are situations were certain combinations of male/female/parallel/tapered NPS and BSP pipe standard can work together - I wonder whether it could be assumed at this stage that if this is the case then the effective engagement lengths can also be borrowed?