Torque

 

Torque

View the maximum target torque values (Nm) for G-S-S Steel EPDM gaskets.

 

DN	PN6	PN10	PN16	PN25	PN40
15	6	11	11	11	11
20	10	16	16	16	16
25	13	21	21	21	21
32	22	36	36	36	36
40	28	45	45	45	45
50	31	58	58	58	58
65	42	77	77	38	38
80	70	45	45	45	45
100	74	49	49	70	70
125	50	64	64	105	105
150	54	89	89	124	124
200	76	123	82	123	155
250	65	102	127	177	234
300	105	105	160	177	245
350	136	133	177	264	345
400	111	160	223	340	515
500	120	188	316	370	437
600	173	250	480	500
700		233	467	700	1400
800		267	533	800	1600
900		300	600	900	1800
1000		333	667	1000	2000

 

Gasket dimensions are to BS EN 1514-1:1997. This means that they are suitable for making flange connections with components whose geometry is that of BS EN 1092-1 and BS EN 1092-2.

The torque specifications are based on a coefficient of friction of μ = 0.12 and a maximum surface pressure of 15 N/mm2, the number and sizes of fasteners comply with detail from tables 11 – 15 within BS EN 1092-1.
A coefficient of friction of μ = 0.12 can be achieved by appropriately lubricating the load bearing surface of the fasteners with WRAS approved Interflon HT1200.

When attempting to make a flange connection with components made of plastic. e.g. PE, please note that the tightening torques must be adjusted according to the respective flange material.

Where geometry between the two flanges is not as detailed by BS EN 1092 it is wise to consider:

• Difference in internal diameters that may lead to increased hydrostatic end thrust.
• Unequal or variance in gasket compression.
• The weakest component within the assembly will dictate the maximum safe target torque.

Amount of Load

We need to control the amount of load that compresses a gasket.

Too little compression and it leaks. Too much and we over compress the gasket which reduces service life and increases the likelihood of mass failure.

We therefore must control the fastener tension created within the flange assembly that in turn gives us compressive load to the gasket. This fastener tension is created when we begin to stretch the bolt. This is known as pre-load. We stretch the fastener by turning the nut, but as the nut gets tighter we build friction. This friction is variable between different metal coatings and increases the more we tighten the nut. We lose bolt tension through lack of, or wrongly applied lubricant.

The amount of load we impart to the flange assembly may need constrained based on the maximum safe load for the weakest component.

When using plastic flanges it is also wise to consider not only the maximum safe strength of the plastic flange but also the backing ring. Careful attention should also be given to flange geometry.

Steel EPDM Gaskets

Looking for Steel Rubber Gaskets? Then contact William Johnston & Company Limited today. We are the leading gasket manufacturers in the UK and have been manufacturing & supplying gaskets for nearly 70 years.

 

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