NPT fitting question

[ptbrakefield]

This is on a pontoon boat, but it's not really a pontoon question.

The plastic plugs in my pontoon have disintegrated. I need to replace them. However, I'm not sure what size NPT plug I need.

How do you measure for the correct size? From the outside, or inside where the taper is narrower?

 

[bigdee]

Hex Socket Pipe Plug, Short Standard On Precision Fittings, Inc.

Browse Hex Socket Pipe Plug, Short Standard in the Precision Fittings, Inc. catalog including Item #,Size & Pitch,BOverall Length,CHex, Across Flats,DNominal Diameter, Ref.,ESocket Depth

pipeplugs.precisionfittings.com

 

[Bondo]

This is on a pontoon boat, but it's not really a pontoon question.

The plastic plugs in my pontoon have disintegrated. I need to replace them. However, I'm not sure what size NPT plug I need.

How do you measure for the correct size? From the outside, or inside where the taper is narrower?

Ayuh,..... It's probably 1/2" pipe,..... very common,......

The other possibility is 3/4" pipe,....

The Od is 'bout 1/4" larger than the actual size,......

 

[1960 Starflite]

Ayuh,..... It's probably 1/2" pipe,..... very common,......

The other possibility is 3/4" pipe,....

The Od is 'bout 1/4" larger than the actual size,......