1

Designing Systems

toCompensate

forThermal

Expansionand

Contraction

Things We Have Learned From Being Sued

2

GapNo Gap

Things We Have Learned

Select a joint with the correct Movement.

Be careful with air

Everything has a pressure limit.

3

Things We Have Learned

Even Stainless Steel can be attacked

4

Things We Have Learned

Rubber joints need to be properly torqued

Rubber joints need to be properly RE-torqued

Rubber joints need to be properly restrained

5

6” Model MC - 6 Corrugations

Anchor Load @ 150psi - 11,600#

Things We Have Learned

Bellows joints need to be properly guided

Bellows joints need to be properly anchored

Anchor loads need to be understood

6

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Riser F3 Floor 4‐25 Room 2‐4

Things We Have Learned

Sometimes people put in too many expansion joints

Sometimes people don’t put in enough expansion joints

Use Any Natural Flexibility In The piping layout

So Where Do We Start?

7

2012 ASHRAE Handbook

Heating, Ventilating, and Air Conditioning Systems and Equipment

Chapter 46

Or this can be simplified to

L = 6.225 √∆D

L = 3∆DE

√(144in²/ft²)SA

Where ∆ = Thermal expansion of leg ABD = Pipe Outside DiameterE = Modulus of ElasticitySA = Allowable Stress

For a Basic Expansion ElbowHard Pipe ∆

L

Anchor

Anchor

A

B

C

L = 4 √∆D Where ∆ = Thermal expansion of leg ABD = Pipe Outside DiameterE = Modulus of ElasticitySA = Allowable Stress

For a Basic Expansion “Z” Bend Hard Pipe

X

X

Guide

Guide

AnchorAnchor

L

L

L

A

B

Anchor to Anchor Expansion

L = 6.225 √∆D

W = L/5

H = 2*W

Where ∆ = Thermal expansion of runD = Pipe Outside DiameterE = Modulus of ElasticitySA = Allowable Stress

For a Basic Expansion Loop Hard Pipe

XX

AnchorAnchor

Guide

Guide

Anchor to Anchor Expansion

2H 2H

W

H

8

What do we do?

So if we do not have enough

natural flexibility

Internally Pressurized

Externally Pressurized

Flexible Pipe Loop

Types of Expansion Joints

Flexible Pipe Loop The flexible pipe loop is also smaller and has less anchor load than a hard pipe loop

Flexible Pipe Loop

On a flex loop the braid is the anchor

9

Corrugated stainless

steel hose by itself

has great hoop

strength, but poor tensile

strength

Hose Basics