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Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

(OP)
Notes from email with a picture. I believe these parts were made in Mexico.
The thread
is not well manufactured(attached photo) but when using the gauge it enters correctly, can it be approved
. (600 pieces).

I looked at this picture and it looks like a straight thread but it's a 1" NPT that gaged to L1. I think because it uses Teflon tape to seal or sealant, the crests aren't so critical. I'm not sure what to check other thn to ask them to make one up to a test plug and pressure test using 4 turns past finger tight.

Thoughts?

RE: Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

Looks pretty normal to me. NPT threads should not have sharp peaks.

RE: Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

That profile is actually not bad. Some crest truncation is tolerable.
I focus on root defects and significant laps on the flanks, but metallography is required for that.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

I've never seen a pipe thread up that close, but shouldn't it have a a ~1.8 deg taper? Is that not what 65CCJ is referring to? My computer optical comparator (aka on screen ruler) is showing near enough to no taper.

edit: regarding the "pressure test" 4 turns _past_ finger tight--not sure it will thread that far before substantial interference from the partial threads (maybe that's your point?). Maybe it will seal, maybe it won't. If you aren't happy with the thread I personally think there is visual evidence (that could also be measured for proof) of the lack of a taper and therefore a non-conforming part; disposition as you see fit.

RE: Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

(OP)
turns out taper is way off in addition to form. It's rolled. 600 pieces may need to be scrapped if not reworkable. Waiting on sample parts to arrive form Mexico.

RE: Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

What is the required standard ?

Regards

RE: Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

(OP)
The standard we reference is ANSI/ASME standard B1. 20.1. but I don't think we actually represent the connection as being made to a standard. I'll have to see but it's probably implied that thread meets ANSI/ASME B1.20.1.

RE: Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

You reference a standard but don't "represent the connection as being made to a standard" -- "probably implied" ? These are all confusing; what does the drawing actually say?

If it says "NPT 1-11.5 per ANSI/ASME B1.20.1" then you are requiring it be made to said standard; heck even if you leave off the reference it still needs to be a "NPT" thread which is defacto tapered. (Note: I don't know what standard they would be making it to if they are claiming it's an NPT thread but just not to said ASME standard.)

If you mean it isn't modeled with the dimensions from the standard that's irrelevant as threads are not typically modeled unless it's a proprietary/unique threadform anyway.

RE: Thread Form isn't correct but gages OK for 1"NPT Male Thread - Is the picture grounds for scrap

(OP)
It calls out simply
the size NPT with no reference to a specification

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