Page 197 - publication

technical data

Introduction

Couplings

Outlets

Fittings

Val

ves &

Accesso

ries

High

Pressure

Advanced Copper

Method (IPS)

DI-LOK

®

Nipples

Plain-End

Fittings

HDPE

Couplings

Sock-It

®

Fittings

Stainless

Steel Method

Roll

Groovers

Installation

& Assembly

Special

Coatings

Design

Services

Technical

Data

Master Format

3 Part Specs.

Pictorial

Index

CTS Copper

System

www.anvilintl.com

197

Thermal growth cannot be stopped. It can only be controlled

by the use of anchors and expansion joints or expansion loops.

It is also important to hang or support the pipe with rolls or

slides and use guides to control the thermal expansion of the

pipe into an expansion joint or expansion loop. The use of static

hangers, such as clevis hangers, should not be considered on

pipe that is thermally expanding. When using trapeze hangers

for multiple systems it is important to have “like” systems on

the trapeze, that is, systems that are operating near the same

temperature. If you combine hot systems with cold systems on

a trapeze, the thermal expansion of the hot system can cause

the trapeze to possibly twist and fail or excessive stress could

be induced on the grooved joints on all of the systems on the

trapeze. Hot systems should be hung or supported indepen-

dently of cold or ambient systems or a means should be provided,

such as pipe rolls or pipe slides, to allow the hot systems to

thermally expand on the trapeze.

If the pipe is a vertical riser then consideration must be given to

the use of spring hangers to allow the pipe to grow vertically

up or down depending upon how the pipe is anchored while

still supporting the pipe. Vertical pipe thermally expands the

same amount as horizontal pipe and this has to be taken into

consideration relating to supports, expansion joints or expansion

loops. If the vertical pipe is supported by friction/riser clamps

only and the pipe expands vertically upward, the clamps will

grow with the pipe off the penetration or supporting structure

and no longer provide support. If the growth is downward, the

friction clamps resting on the penetration or supporting

structure can either fail or the pipe may overcome the friction

force and push it’s way through the clamp as the pipe thermally

expands downward. In either case the clamps are no longer

supporting the pipe as intended and this may induce excessive

stress on the grooved joints.

Whether it is horizontal or vertical grooved pipe, growth of the

piping system due to pressurization and thermal expansion must

be considered. On hot systems, both must be taken into account

and added together to determine the overall growth of the

system and the effect on the hangers or supports that are used.

In the previous examples, pressurization expansion on the 400

ft. run of pipe was 4.75" for a fexible joint system and 1.78" for

a rigid joint system and the thermal expansion was 3.04". Adding

these combinations together would result in a total pipe growth

of 7.79" for a fexible system or 4.82" for a rigid system, regardless

of the horizontal or vertical orientation of the pipe. Again, this

is a signifcant amount of growth relating to hangers and supports

and the resulting stresses induced on grooved joints.

CONSIDER SOME RESTRAINT

Although grooved systems in seismic zones perform extremely

well, consideration should be given to how a grooved system

is seismically restrained. If you have growth due to pressurization

and/or thermal expansion consideration should be given on

how to restrain the system while still allowing growth to occur.

Seismic restraints in the longitudinal direction of a long pipe

run may restrict the growth of the pipe inducing stresses into

the grooved couplings. Seismic restraints in the lateral direction

should have little impact on expansion except where the

system has a change in direction. If the seismic restraints are

placed laterally after a change in direction at the end of a long

run of pipe, the expansion of the long pipe run may be restricted

and this could induce excessive stress into the grooved joints.

By reviewing the couplings to be used on a project, pressurization,

thermal expansion and seismic restraints, one can best determine

the proper selection and application of hangers and supports

for a grooved piping system. This will, in turn, help ensure that

grooved piping systems will continue to enjoy a solid reputation

in the areas of maintenance and downtime.

PIPE SUPPORT

Considerations for the Hanging or Supporting of Grooved Piping Systems

upper

intermediate

lower

Clevis Hanger Assembly

upper

intermediate

lower

Double Bolt Pipe

Clamp Assembly

upper

intermediate

lower

Trapeze Assembly

upper

intermediate

lower

Spring Riser Hanger Assembly

GL-2.10