Pg Steel Conduit Threads are manufactured per DIN 40430. WESTport manufactures Pg Steel Conduit Thread Ring Gages per DIN 40431.
The Pg thread series is designed for use with the thin wall cross section of the steel conduit. The thin wall thickness requires a shorter profile thread that will not break through the outside diameter of the steel conduit during the machining process. The Pg conduit thread form features an 80° included angle and a shorter profile than the 60° included angle found in the Unified National thread series and the Metric thread series.
The DIN 40431 standard for P1 steel conduit threads specifies the requirements for using GO thread ring gages and plain NOGO ring gages to inspect the conduit threads. A unique aspect of the Pg Steel Conduit Thread Ring Gage is that the NOGO member is a plain cylindrical gage. This works because as the thread is machined the crest if the thread comes to a point. As the thread size is changed, the position of the point changes and as a result can be measured. The plain NOGO ring gage checks the major diameter or crest of the thread and verifies that minimum material condition is met. The GO threaded ring works normally by ensuring the maximum material condition is met.
Pg Conduit thread ring gages are easy to use:
1. The GO Threaded ring gage must be capable of being screwed by hand without undue force over the full length of the threaded work piece
2. The NOGO plain ring gage must not be able to pass over the threaded work piece.