Calibration Check Points for ACME & LPT Thread Plug & Rings

[rnsvasan]

Can anyone explain what are all the dimensions / parameters to be checked / ensured for ACME & LPT thread Plug & Ring gauge

 

[Jeff Frost]

I would recommend that you obtain the specification for ACME and LPT thread Plug & Ring gages. Typically these specifications also contain information for calibration and certification.

 

[Jim Wynne]

If you don't have it already, I suggest that you obtain a copy of Machinery's Handbook, often referred to as the Machinist's Handbook. It'll tell you everything you need to know about thread standards, among many other subjects. Don't leave home without it.

 

[Stijloor]

I found this for ACME threads.

Stijloor.

 

[Wayne]

Can anyone explain what are all the dimensions / parameters to be checked / ensured for ACME & LPT thread Plug & Ring gauge

The easiest way to get the specific dimensions you seek is to order Long Form Certifications with your new gages. The certifications will have all the required measurable data points identified with the associated tolerances; however; this does not give you official supporting documentation.

The official standards can be purchased from several outlets, and if you are calibrating the gages you should have a copy of the standard as your base reference document. One source of the documents is: Global Engineering Documents.
For ACME search for B1.5.
For NPT search for B1.20.1.

The thread gage requirements can be generated by computer using ThreadTech Software. There is a free 10-day trial version available.

Calibrating ACME is fairly straight forward; use wires to check your plug gages and set plug gages to set your rings. Avoid using direct measurement on adjustable style ring gages like the plague. The methodology is fraught with hidden problems.

Calibrating NPT is best done with master gages. I recommend sending the masters out to a gage maker to be calibrated. Don't do them yourself.

Hope this helps some.

 

[Wes Bucey]

After nearly ten years of dealing with tapered threads (NPT), I absolutely agree with Wayne that calibration by professional service is well worth the cost versus trying to do it in-house.

ACME is pretty straightforward. You could do it yourself, but why?

Machinery's Handbook (don't stint - buy the latest edition -check it out here Educational and Technical Books Supporting Smart Manufacturing Industrial Press: Educational and Technical Books Supporting Smart Manufacturing

is good advice and a great reference book for EVERY industrial facility.

Thread Standards can be had direct from ASME
The American Society of Mechanical Engineers
Use "pipe threads" as search term on their site.