Why aren’t metal straps allowed on plastic drain pipes?
Like this?
Yep.
Not a problem around here…
I haven’t heard that. Thats how most drain pipes are supported around here.
It says right here in my code book that its not allowed and even has a picture with an arrow through it. It says only listed plastic hooks. I just don’t know why.
First for me never heard that before
It has been that way since approx. 2006 (maybe longer & plastic pipe only). Reason being, wire and Plumbers tape (metal) fail to resist “upward thrust” and lateral movement from water surge and expansion/contraction, and can cut/damage the piping. If a solid brace (such as a v-notched board) was installed between the pipe and the floor/ceiling above (at the strap), it would usually be allowed.
That’s my understanding also, that the metal straps can cut into the plastic pipes.
Hangers and anchors shall be of sufficient strength to maintain their proportional share of the weight of pipe and contents and of sufficient width to prevent distortion to the pipe. Hangers and strapping shall be of approved material that will not promote galvanic action. Rigid support sway bracing shall be provided at changes in direction greater than 45 degrees for pipe sixes 4 inches or larger.
Reference please. What code book? What code section?
Aaaah thanks Jeff.
Are you asking because you are curious or you don’t believe me.
Section 2605 of the IRC and Section 304 of the UPC
P2605.1 General. Piping shall be supported in accordance
with the following:1. Piping shall be supported to ensure alignment and prevent
sagging, and allow movement associated with the
expansion and contraction of the piping system.
- Piping in the ground shall be laid on a firm bed for its
entire length, except where support is otherwise provided.
3. Hangers and anchors shall be of sufficient strength to
maintain their proportional share of the weight of pipe
and contents and of sufficient width to prevent distortion
to the pipe. Hangers and strapping shall be of approved
material that will not promote galvanic action. Rigid support
sway bracing shall be provided at changes in direction greater
than 45 degrees (0.79 rad) for pipe sizes 4 inches (102 mm) and larger.
- Piping shall be supported at distances not to exceed those
indicated in Table P2605.1.
Code Commentary: The intent of supporting the pipe is to maintain proper
slope and alignment and to prevent sagging, while allowing
movement of the pipe resulting from expansion
and contraction [see Commentary Figure P2605.1(2)].
Hangers and supports for piping must be capable of
supporting the load imposed by the piping system and
must not be detrimental to the pipes they support. Using
hanger or strapping material that is not compatible
with the piping material can result in corrosion caused
by galvanic action. Galvanic action occurs when dissimilar
metals are in contact in the presence of an
electrolyte. Section P2605.1 also contains lateral support
requirements. Pipes are subject to the momentum
resulting from the flow of waste. Hangers alone may
not be sufficient to resist these forces, and, thus, rigid
support sway bracing is required for pipe sizes 4
inches (102 mm) or larger at changes of direction
greater than 45 degrees (0.79 rad) [see Commentary
Figures P2605.1(1) and P2605.1(3)].
Code Definitions:
APPROVED. Acceptable to the building official.
Throughout the code, the term “approved” is used to
describe a specific material or method of construction,
such as the approved drainage system mentioned in
Section R408.5. Where “approved” is used, it means
that the design, material or method of construction is
acceptable to the building official. It is imperative that
the building officials base their decision of approval on
the result of investigations, tests or accepted principles
or practices.
In consideration of the above code, I would not have a problem ‘approving’ metal hangers for use with plastic pipe. That is the norm around here.
Nothing in that posted code section prevents metal pipe strap on PVC pipe so I agree with Joe.
There is no galvanic possibility on PVC
I have never heard of a prohibitions on metal pipe strap on Plastic DWV.
Please post the relevant section.
Just sayin.
What’s your point? That has nothing to do with the OP.
If you weren’t so closed minded, and actually read the progression of posts leading up to your’s, you would see the relevancy.
As usual, I’m done with you.
1 Like
Start a new thread if you want to talk about anything other than metal straps on drain pipes. :-;;