One-piece bend with ArmAflex Sheet

ApplicAtiOn AreAS

This method for insulating pipework bends saves time

and material.

Producing bend covers using a single piece of Armaflex

is particularly suitable for heating and hot process pipes.

The method may also be used on cold, chilled and re-

frigerant lines provided careful attention is paid to en-

sure all adhesive seams are fully vapour sealed.

prOduct recOmmendAtiOn

One-piece bends as detailed below can be fabri-

cated from the following Armacell products:

• AF/Armaflex

• Armaflex IT

• Armaflex AC

• HT/Armaflex

• NH/Armaflex

Note: The number of chevrons required will vary

dependant on the material in use, the pipe diame-

ter, the insulation thickness and the operating line

temperature.

methOd 1: SeAm On inSide Of bend

1. Determine the circumference (C) of the pipe using a

strip of Armaflex of the thickness to be installed.

Note: Do not stretch the strip

Le

Li

2. Determine the outside length of the bend (Le) and the

inside length of the bend (Li) using a strip of Armaflex

of the thickness to be installed.

Note: Do not stretch the strip

Le

C

1 /3 C

1 /3 C

1 /3 C

3. Cut a piece of Armaflex sheet into a rectangle with

width equal to the circumference of the pipe (C) and

length at least equal to the outside length of the bend

(Le) .

4. Using a ruler and silver coloured pen divide the

circumference (C) into three equal sections as marked

on the diagram above.

5. Determine the number of chevrons which should be

cut using the table below.

Sheet Thickness

Number of Chevrons needed

≥ 88.9 ≥ 114 ≥ 163 ≥ 219 ≥ 273

9 mm 2 3 3 4 5

13 mm 2 3 3 4 5

19 mm 3 3 4 5 6

25 mm 3 4 5 5 6

32 mm 4 5 5 6 7Note: The values in the above table are indicative minimum values only, applicable for Class O Armaflex only. As a general rule smoother results will be obtained as the number of chevrons is increased.

6. Divide the length of the inside bend (Li) by the

number of chevrons to be cut (n) minus one to give

the value X.

Divide the difference between the outside length of

the bend (Le) and the inside length of the bend (Li)

by the number of chevrons to be cut to give the

value Y.

1 /3 C

1 /3 C

1 /3 C

XYXY

XYXY

Y

Y

7. Using these calculated values of X and Y divide the

longer edge of the Armaflex (Le) into alternating

lengths of Y and X as shown above.

Use these markers to draw n isosceles triangles of

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© ARMACELL GMBH

height 1/3 C and width Y as shown. Cut each of

these triangles from the Armaflex using a sharp

knife.

1 /3 C

1 /3 C

1 /3 C

XYXY

XYXY

Y

Y

8. Repeat this process on the opposite side to give a

shape similar to that shown above.

9. Apply Armaflex Adhesive on the inside of each

chevron. Allow the adhesive to tack dry before

closing the seam and naturally bending the Armaflex

sheet.

Note: For best results pinch the widest part of the

chevron closed first before moving along to seal the

rest of the chevron.

10. Apply Armaflex Adhesive to each side of the seam.

Place the Armaflex piece around the bend, allow the

adhesive to tack dry and then press the joint faces

firmly together.

11. Wet seal jointing details with adhesive, fitted under

slight compression, to complete the bend.

methOd 2: SeAm On OutSide Of bend

1. Determine the circumference (C) of the pipe using a

strip of Armaflex of the thickness to be installed.

Note: Do not stretch the strip

Le

Li

2. Determine the outside length of the bend (Le) and the

inside length of the bend (Li) using a strip of Armaflex

of the thickness to be installed as described in the

application advice “how to correctly measure

bends”.

Note: Do not stretch the strip

3. Cut a piece of Armaflex sheet into a rectangle with

width equal to the circumference of the pipe (C) and

length at least equal to the outside length of the bend

(Le).

Le

C

½C

4. Using a ruler and silver coloured pen divide the

circumference (C) by 6 and mark 1/6 C from each

side of the square as shown above.

5. Determine the number of chevrons which should be

cut using the table below.

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APPLICATION TIP One-Piece-bend >> Using Armaflex Sheets

Sheet Thickness

Number of Chevrons needed

≥ 88.9 ≥ 114 ≥ 163 ≥ 219 ≥ 273

9 mm 2 3 3 4 5

13 mm 2 3 3 4 5

19 mm 3 3 4 5 6

25 mm 3 4 5 5 6

32 mm 4 5 5 6 7Note: The values in the above table are indicative minimum values only, applicable for Class O Armaflex only. As a general rule smoother results will be obtained as the number of chevrons is increased.

6. Divide the length of the inside bend (Li) by the

number of chevrons to be cut (n) minus one to give

the value X.

Divide the difference between the outside length of

the bend (Le) and the inside length of the bend (Li)

by the number of chevrons to be cut to give the

value Y.

7. Using these calculated values of X and Y divide the

centre line of the Armaflex (Le) into alternating

lengths of X and Y as shown below.

Le

C

½C

X YYXY

Use these markers to draw n diamonds of width

2/3 C and height Y as shown. Cut each of these

diamonds from the Armaflex using a sharp knife.

8. Apply Armaflex Adhesive on the inside of each

diamond. Allow the adhesive to tack dry before

closing the seam and naturally bending the Armaflex

sheet.

Note: For best results pinch the widest part of the

diamond closed first before moving along to seal the

rest of the chevron.

9. Apply Armaflex Adhesive to each side of the seam.

Place the Armaflex piece around the bend, allow the

adhesive to tack dry and then press the joint faces

firmly together.

10. Wet seal jointing details with adhesive, fitted under

slight compression, to complete the bend.

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One-Piece-bend >> Using Armaflex Sheets APPLICATION TIP

© ARMACELL GMBH

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hOw tO cOrrectlY meASure bendS

In order to measure the length and radius of a bend it is

necessary to first identify the weld seams of the bend.

The bend begins and ends at these weld seams.

Note: The weld seams may not always be immediately

visible. In these cases it will be necessary to judge by

eye.

» the radius of the bend

r

Drop a vertical line from one weld seam and draw a hori-

zontal line from the other weld seam. The point at which

the two lines intersect is the origin of the bend radius.

The distance from the origin of the bend radius to the

pipe is known as the radius of the bend.

» the outside length of the bend

Along the outside of the bend press a strip of Armaflex

of the thickness to be installed. Mark the beginning and

end of the bend (from weld seam to weld seam) onto the

Armaflex strip.

Remove the Armaflex strip and place flat onto a work

surface. Now measure the distance marked. This dis-

tance is referred to as the “outside length of the bend”.

» the inside length of the bend

Along the inside of the bend press a strip of Armaflex of

the thickness to be installed. Mark the beginning and

end of the bend (from weld seam to weld seam) onto the

Armaflex strip.

Remove the Armaflex strip and place flat onto a work

surface. Now measure the distance marked. This dis-

tance is referred to as the “inside length of the bend”.

All statements and technical information are based on results obtained under typical conditions. It is the responsibility of the recipient to verify with us that the information is appropriate for the specific use intended by the recipient. For updates to this document please refer to our website www.armacell.com.

© Armacell GmbH · Subject to alterations · Printed in UK · 2009 · OnePieceBend-005-EN-INT

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APPLICATION TIP One-Piece-bend >> Using Armaflex Sheets