Bolt Torques

Lined Pipe and Fittings

Bolting Materials should be of good quality, clean and well lubricated and to the site standard. The use of washers is recommended to ensure correct even torque. Bolts should be brought finger tight and then tightened through the use of a torque wrench in strict sequence of diagonally opposite pairs. This, and all subsequent torquing, of bolts should be undertaken at ambient temperature.


*Torque bolts diagonally opposite each other in pairs

Please note that PTFE is suject to cold flow or "creep".  It is therefore strongly recommended that all bolts are retorqued a minimum of 24 hours after commissioning or following the initial full process cycle. The torque of all bolted joints should then be rechecked at least annually thereafter.

The following table gives recommended torque levels for flange to flange connections.

Nominal Bore

Torque

Bolts/Studs

Imp

Metric

Ft Ibs

Nm

Qty

(Metric)

(UNC)

1"

25

14

19

4

M12

1/2"

1.1/2"

40

20

27

4

M12

1/2"

2"

50

35

47

4

M16

5/8"

3"

80

54

73

4

M16

5/8"

4"

100

40

54

8

M16

5/8"

6"

150

80

108

8

M20

3/4"

8"

200

100

136

8

M20

3/4"

10"

250

94

127

12

M24

7/8"

12"

300

107

145

12

M24

7/8"

The torque values given above are a guide; they may be exceeded by a value of 50% to effect a seal.  If once this torque level has been reached a seal has not been achieved, it is likely that there is another cause.

This may be due to joint misalignment or strain, or it may be that the PTFE flare face has suffered mechanical damage.  Small scratches can be removed with the use of a fine abrasive without detriment.  If damage is significant, overtightening is not a solution and the component should be rejected.

Contact Details

Corrosion Resistant Products Ltd
Todmorden Road
Littleborough
OL15 9EG

Phone: +44(0)1706 756400
Fax: +44(0)1706 379567
Email: