Rider Rick
Silver Member
- Joined
- Oct 19, 2009
- Messages
- 468
I failed a plumber for a flex line on a T&P relief line off a water heater because the inside diameter was smaller than the inside diameter T&P valve.
The plumber said that the ID of a 3/4" flex line is the same as the ID of the 3/4" CPVC pipe.
I said the code requires the relief valve drain pipe with fittings that will not reduce the interal bore of the pipe and extend from the valve to the outside.
Also I would post on the BB about the ID of 3/4" CPVC pipe for relief valves.
I recieved this e-mail from that plumber today:
Subject: RE: relief line on water heater
Rick,
I have some information on the T&P relief line off a water heater. On most relief valves there is a
mark stating NPS standing for Nominal Pipe Size, or NPT for Nominal Pipe Tube. On a ¾” relief
valve any listed ¾” pipe will approved for relief lines can be used. The ID does not matter.
The statement “does not reduce the bore…” refers to a smaller listed pipe (i.e. ½”) or some
non-listed fitting (possibly a water heater flex).
The 2010 UPC Answers & Analysis Committee answered Item #10-01 as follows:
No. Nominal pipe size does not refer to an exact ID or OD of a pipe. It is the
name given to a pipe size and used in the sizing tables in chapter 6 and
appendix A. Industry standards have set the OD’s of different pipe materials
to facilitate the use of fittings and pipe threads etc that work for a number of
pipes. For instance, ¾ copper tube may be used in type K, type L or Type M
pipe. The OD of all three is the same while the ID is different on each. They
are all called ¾ pipe and all use the same fittings to join them.
Considering this issue were Chairman, John J. Roth, City of Houston, TX (Retired); Rex
Crawford, City of Lincoln, NE; Steven Nastruz, Seattle/King County, Seattle, WA; Bruce
Pfeiffer, City of Topeka, KS; Ed Schoenfeld, City of Salt Lake City, UT; G.F. “Jed”
Scheuermann, City of Portland, OR; K. Anthony Wilcockson, City of Walnut Creek, CA
(Retired); Trini Mendoza, County of Ventura, CA and Alfred Ortega, City of Houston, TX.
Thank you for your patience and interest in clarifying this matter.
With this information I will stop using the ¾” nut by nut flex line coming from the relief and
start using ¾” CPVC pipe and fittings to the outside of the house.
This clears up some of the doubt on the ID bore of ¾” CPVC.
Have a good day
The plumber said that the ID of a 3/4" flex line is the same as the ID of the 3/4" CPVC pipe.
I said the code requires the relief valve drain pipe with fittings that will not reduce the interal bore of the pipe and extend from the valve to the outside.
Also I would post on the BB about the ID of 3/4" CPVC pipe for relief valves.
I recieved this e-mail from that plumber today:
Subject: RE: relief line on water heater
Rick,
I have some information on the T&P relief line off a water heater. On most relief valves there is a
mark stating NPS standing for Nominal Pipe Size, or NPT for Nominal Pipe Tube. On a ¾” relief
valve any listed ¾” pipe will approved for relief lines can be used. The ID does not matter.
The statement “does not reduce the bore…” refers to a smaller listed pipe (i.e. ½”) or some
non-listed fitting (possibly a water heater flex).
The 2010 UPC Answers & Analysis Committee answered Item #10-01 as follows:
No. Nominal pipe size does not refer to an exact ID or OD of a pipe. It is the
name given to a pipe size and used in the sizing tables in chapter 6 and
appendix A. Industry standards have set the OD’s of different pipe materials
to facilitate the use of fittings and pipe threads etc that work for a number of
pipes. For instance, ¾ copper tube may be used in type K, type L or Type M
pipe. The OD of all three is the same while the ID is different on each. They
are all called ¾ pipe and all use the same fittings to join them.
Considering this issue were Chairman, John J. Roth, City of Houston, TX (Retired); Rex
Crawford, City of Lincoln, NE; Steven Nastruz, Seattle/King County, Seattle, WA; Bruce
Pfeiffer, City of Topeka, KS; Ed Schoenfeld, City of Salt Lake City, UT; G.F. “Jed”
Scheuermann, City of Portland, OR; K. Anthony Wilcockson, City of Walnut Creek, CA
(Retired); Trini Mendoza, County of Ventura, CA and Alfred Ortega, City of Houston, TX.
Thank you for your patience and interest in clarifying this matter.
With this information I will stop using the ¾” nut by nut flex line coming from the relief and
start using ¾” CPVC pipe and fittings to the outside of the house.
This clears up some of the doubt on the ID bore of ¾” CPVC.
Have a good day
