 |
 | |
     | ||
|
Tapered Gages / NPT / NPTF / ANPT GAGING PRACTICE
A.N.P.T (Aeronautical National Pipe Taper)
TO GAGE INTERNAL A.N.P.T TAPER PIPE THREADS, check first with the A.N.P.T. L-1 thread plug gage. This plug differs in dimensions from the N.P.T. plug and has minimum and maximum steps in addition to the basic step. If the face of the product is between the minimum and maximum steps of the plug, the product is in tolerance. The A.N.P.T. L-3 plug gage is used to check the three threads beyond the L-1 depth. As a check on taper the "reading" on the L-3 thread plug must be within one-half turn of the "reading" on the L-1 thread plug gage. The truncation is checked with the six-step plain taper plug gage. This plug has minimum and maximum truncation steps for each of the three pitch diameter conditions - Minimum, Maximum and Basic. If the L-1 Plug shows the product to be basic pitch diameter, the face of the product should lie between the basic minimum and the basic maximum steps of the truncation plug. If the pitch diameter is minimum the part should fall between the MN and MNT step. If the pitch diameter is maximum the part should fall between the MX and MXT steps. No appreciable shake or wobble is permitted. Shaky fit indicates taper error. TO GAGE EXTERNAL A.N.P.T. TAPER PIPE THREADS, first check with the A.N.P.T. L-1 thread ring. The small end of the ring must be within one turn plus or minus of being flush with the end of the product thread. Note exactly what this "standoff" is and compare it with the "standoff" with the A.N.P.T. L-2 thread ring. As a check on taper the total tolerance on standoff variation between the L-1 and L-2 rings must not exceed one-half turn. The truncation is checked with the six-step plain taper ring gage. This ring has minimum and maximum truncation step with each of the three pitch diameter conditions - Minimum, Basic, and Maximum. If the L-1 ring shows the part to be basic pitch diameter the end of the part should fall between the B and BT steps on the six-step plain ring. If the pitch diameter is minimum the part should fall between the MN and MNT step. If the pitch diameter is maximum the part should fall between MX and MXT steps. No appreciable shake or wobble should be permitted. Lead, angles and root truncation should be checked whenever possible, by projection as a check on tool wear. See Military Standard MIL-7105 latest edition for complete specifications. N.P.T.F. (National Pipe Taper Dryseal Pressure - Tight Joints)
N.P.T.F. EXTERNAL TAPER PIPE THREADS are checked in the same manner as A.N.P.T. threads. Gages are dimensionally different, however, and must not be interchanged. The turns method may be substituted for the "standoff" method to compensate for gage and product chamfers. A tolerance of plus or minus one turn is permitted from the basic number of turns specified. As a check on taper the difference in turns engagement with the L-1 and L-2 Dryseal rings shall be within one-half turn of the difference between the basic turns engagement of the ring gages.  Thread and Plain Plugs Thru 20" - Precision Lapped
 A.N.P.T. (Aeronautical National Pipe A Taper) N.P.T.F. (National Pipe Taper Dryseal Pressure-Tight Joints)
Sizes not shown contact for pricing & availability Home | Contact Us | Unified Reversible Thread Plug Gages | Unified Taperlock Thread Plug Gages Unified Thread Ring Gages & Truncated Thread Setting Plug Gages | Unified HILO Thread Setting Plug Gages HILO™ Takes The Guesswork Out Of Setting Adjustable Ring Gages | Metric Thread Gages | Master Setting Discs 1, 2 & 3 Cylindrical Reversible Pin Type/Taperlock/Trilock Plugs | Cylindrical Plain Rings Steel & Carbide | Reversible Trilock Design Cylindrical Plug Gages & Midget Thread Trilocks - Reversible | Pipe Thread Gages | Gaging Practices | Basic Dimensions of Taper Pipe Threads API Thread Gages | SquareMaster™ | Metrology Equipment | Gage Calibration Services | International Gage Standards | Special Gages |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
