Designing Systems to Compensate for Thermal Expansion and Contraction

Designing Systems to Compensate for Thermal Expansion and Contraction

Things We Have Learned From Being Sued

6 Model MC - 6 Corrugations Anchor Load @ 150psi - 11,600#

This is why you should use guides

Riser F3 Floor 4 25 Room 2 4

Use Any Natural Flexibility In The piping layout

2008 ASHRAE Handbook Heating, Ventilating, and Air Conditioning Systems and Equipment Chapter 45

For a Basic Expansion Elbow Hard Pipe Anchor A Δ L = 3ΔDE B L (144in²/ft²)S A C Where Δ D E S A = Thermal expansion of leg AB = Pipe Outside Diameter = Modulus of Elasticity = Allowable Stress Anchor Or this can be simplified to L = 6.225 ΔD

For a Basic Expansion Z Bend Hard Pipe L = 4 ΔD Where Δ = Thermal expansion of leg AB D E S A = Pipe Outside Diameter = Modulus of Elasticity = Allowable Stress Anchor A Anchor Guide L B L L Guide Anchor to Anchor Expansion

So what kind of expansion joint to use?

For a Basic Expansion Loop Hard Pipe L = 6.225 ΔD W = L/5 H = 2*W Where Δ D E W S A = Thermal expansion of run = Pipe Outside Diameter = Modulus of Elasticity = Allowable Stress Anchor Guide H Anchor 2H 2H Guide Anchor to Anchor Expansion

Hard Loops Pro/Con Pro Same material as the rest of piping Constructed on site Medium anchor loads Grandfather used em Con Constructed on site, costly to fabricate, hang and insulate Needs lots of room High lateral loads on moment guides.

Flexible Expansion Loop

V Loops

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

Hose Basics

Corrugated stainless steel hose by itself has great hoop strength, but poor tensile strength

Virtually any amount of movement

Cap weld, welding the hose, braid and collar together

Weld the End Fitting to the Hose

On a flex loop the braid is the anchor

4 Sch 40 Carbon Steel With Hard Pipe Expansion 90 4 Sch 40 Carbon Steel With H&B Dog Leg 165 Feet 2.85 Exp. Anchor with 582 pounds force Guides 165 Feet 2.85 Exp. Anchor with 180 pounds force Guides 19 Feet 3 Feet 19 Feet 50 Feet.59 Exp. Hose & Braid 3 Feet 50 Feet.59 Exp.

Flexible Loop Pro/Con Pro Very compact Large movement Con Some pressure limitations Standard or custom fit Least expensive option Seismic capable Lowest anchor loads, almost no structural considerations. Minimal guiding requirements No maintenance

There s a lot of choices of Axial movement Bellows Lateral movement Angular movement Axial Bellows Externally Pressurized Axial Bellows Untied Double Bellows Gimbal Bellows Dual Tied Bellows Single Hinge Bellows Double Hinged Bellows

Internally Pressurized Externally Pressurized Capable of Axial, Lateral and Angular movements. Axial movement only

Expansion Compensators externally pressurized Atmosphere Built in Liner

Squirm- Strut Instability - Limits the movement of internally pressurized bellows The balance between the number of convolutions needed for the movement exceeds the stability of the bellows

Internally Pressurized Bellows Axial Are Primarily Designed to Handle Axial Movement

On the other hand, a dual-tied bellows moves Axially And laterally

Dual-tied bellows joint

Anchors

Calculating forces on anchors Pressure Thrust Pressure effective area ( Use test pressure if greater ) Deflection Load Published Spring Rate movement of the joint Frictional Resistance Total weight of pipe, media, insulation & equip. coefficient

Calculating forces on anchors Pressure Thrust Pressure effective area ( Use test pressure if greater ) Example: 4 = 35.96 sq. in effective area x 125 PSI = 4495 #.

To calculate the thrust load: Effective Areas

Pressure Thrust for the Model MC Ring Controlled Self-Equalizing Expansion Joint The average car weighs only 3000#

Deflection Load (spring rate) Totally independent of pressure or temperature

Deflection Load on Anchors Published Spring Rate Actual movement of the joint Example: 4 with 6 Axial = Spring rate of 143 lbs/in 4.3 (total amount of expansion) = 614.9 lbs

Calculating forces on anchors Frictional Resistance Total weight of pipe, media, insulation & equip. coeff. Example 4 sch. 40 pipe at 10.8 #/ft x 75 ft = 1890 # 4 pipe internal area 12.73 sq.in. / 144 in. per sq.ft. = 0.088 cu.ft. x 175 linear ft. = 15.4 cu.ft. total volume 125 PSI steam = 3.23 cu.ft. per pound = 4.76# weight add guides & joint & insulation at 500# Total 2395# x 0.3 Coeff. = 719# frictional resistance

Total Anchor Force 4495 Pressure Thrust 614 Deflection Load 719 Friction Resistance 5,828.9 lbs force The engineer may add other loads such as snow, ice, wind, based on project conditions

Intermediate Anchors Intermediate anchors between expansion devices do not see the full load. Intermediate Anchor Main Anchor Expansion Joint Main Anchor EJMA recommends to design intermediate anchors for the spring load of one of the joints

Anchors at fittings can have multidirectional loads Force Main Anchor Expansion Joint Force

Expansion Joint Location Makes a Difference

Guiding

Column strength of pipe.

Remember our Example Total Anchor Force 4495 Pressure Thrust 614 Deflection Load 719 Friction Resistance 5,828.9 lbs force

When velocity is high and could set up vibration in bellows LINERS Compressed air lines Exhaust gases Abrasive flow media Rule of Thumb :When velocity > 10 FPS

Install 1st. Guide a max. of 4 pipe dia. From the expansion joint. Install 2nd. Guide a max. of 14 pipe dia. From the 1st. Guide. Additional guides as per EJMA recommendations

Bellows Pro/Con Pro Low/ no pressure drop Very compact No maintenance Custom fit Easy to insulate Externally pressurizedlarge movement Con High anchor loads Engineered anchors Considerable guiding requirements Torque can be a problem

Slip type Joints

Slip Type Joint

Slip Joint construction detail

Ball Joints Always in, at least pairs Similar construction with Slip joints Same maintenance issues

Slip Type Pro/Con Pro Low/ no pressure drop Very compact Large movement Custom fit Con High anchor loads Engineered anchors Crucial and Considerable guiding requirements Very High maintenance packing frequently needed Low or no cycling is a detriment. Very expensive

Lets Start With Determining The Pipe Size and Pipe Dimensions 150 12 8 250 75 150 6 75 85 75

To Calculate Expansion 1 Determine design temperature for example 200 F. 2 Establish installation temperature - For example 50 F 3 Find the expansion rate per 100 feet 1.179 / 100 feet for steel 1.728 / 100 feet for copper 4 Determine the length of pipe run for example 165 feet 5 Multiply the expansion rate by the length. (165 / 100) 1.179 = 1.94 Expansion 6 If the joint is for both thermal and seismic, the values must be added together!

For An Example Lets use Pipe Material Carbon Steel Service Hot Water Design Temperature 200 F Installation Temperature 50 F Temperature Difference ΔT 150 F Expansion Rate ΔL 1.179 inches / 100 Feet

Lets Calculate How Much The Pipe Will Expand 150 1.77 12 8 250 75 2.95 0.88 150 1.77 6 75 0.88 85 75 1.0 0.88

Lets Establish The Anchor Points Anchor (typ) Anchor (typ) 150 1.77 12 8 250 75 2.95 0.88 150 1.77 6 75 0.88 85 75 1.0 0.88

First check for for Natural Flexibility

Keep in Mind 90 changes in direction are the most efficient piping configuration to use to take up thermal expansion or contraction. Smaller angles will compound the movements!

Next, Use Any Natural Flexibility Of The System Anchor (typ) Anchor (typ) 150 1.77 12 8 22 250 75 2.95 0.88 150 1.77 13 6 75 0.88 85 75 1.0 0.88

Next, Complete The System With Flexible Pipe Loops Anchor (typ) Anchor (typ) MLW80800 150 1.77 12 8 MLW81200 22 250 75 2.95 0.88 MLW30600 150 1.77 13 6 75 0.88 85 75 1.0 0.88

Or, Complete The System With Expansion Joints Anchor (typ) Anchor (typ) 150 1.77 12 8 250 75 2.95 0.88 150 22 1.77 Don t forget about the guides. Note the placement of the Metragators 13 6 75 0.88 85 75 1.0 0.88

What if the 75 foot run was only 18 feet? Anchor (typ) Anchor (typ) 150 1.77 12 8 22 250 75 2.95 0.88 150 1.77 13 6 75 0.88 85 75 1.0 0.88

Option 1 Use a Hose & Braid Dog Leg Anchor (typ) Anchor (typ) 150 1.77 12 8 40 250 18 2.95 0.21 150 1.77 13 6 75 0.88 85 75 1.0 0.88

Option 2 Add an Anchor, and another expansion device Anchor (typ) Anchor (typ) 150 1.77 12 8 18 250 18 2.95 0.21 150 1.77 13 6 75 0.88 85 75 1.0 0.88

Next, Complete The System With Flexible Pipe Loops Anchor (typ) Anchor (typ) MLW80800 150 1.77 12 8 MLW81200 250 18 2.95 0.21 18 MLW30600 150 1.77 MLW30800 13 6 75 0.88 85 75 1.0 0.88

Or with Expansion Joints Anchor (typ) Anchor (typ) 150 1.77 12 8 22 250 18 2.95 0.21 150 1.77 13 6 75 0.88 85 75 1.0 0.88