Black Cast Iron Lock Nut

• Material : Black malleable iron
• Colour : Grey / Dark grey

The black cast iron lock nut (ref. 312) is a recessed hexagonal nut that screws onto a male thread to lock a fitting in position. It prevents accidental loosening caused by vibrations or thermal stress.

What is a lock nut used for?

In plumbing, some fittings (nipple, extension, valve…) must be immobilised after tightening. The lock nut screws against the female fitting into which the male thread is engaged: the two pieces lock against each other. This double-locking principle is essential on installations subject to vibrations or thermal cycles.

In industrial-style decoration, the lock nut can also serve as an aesthetic element or a stop on a threaded pipe.

Specifications

• Standard : Manufactured per EN 10242 and ISO 49. Malleable iron grade EN-GJMW-400-5 (per EN 1562).
• Thread : Female parallel thread (Rp), per ISO 7-1 (BSP).
• Reliability : 100% leak-tested.
• Material : black malleable iron
• Colour : dark grey

Service conditions

• Max temperature : 155°C (water).
• Compatibility : Drinking water, wastewater, gas, steam, non-corrosive liquids.

Dimensions

Scroll the table horizontally to see all measurements.

Size (inches)	DN	Ø int×ext (mm)	a (mm)	e approx. (mm)	s (mm)	Weight (kg)
1/4"	DN8	8×13	6	22	19	0,013
3/8"	DN10	12×17	8	28	24	0,021
1/2"	DN15	15×21	8	37	32	0,028
3/4"	DN20	20×27	9	42	36	0,033
1"	DN25	26×34	10	53	46	0,065
1"1/4	DN32	33×42	11	62	54	0,095
1"1/2	DN40	40×49	12	68	60	0,110
2"	DN50	50×60	13	86	75	0,170
2"1/2	DN65	65×76	19	110	95	0,364
3"	DN80	80×90	22	120	105	0,421
4"	DN100	102×115	—	—	—	0,960

a = height. e = corner-to-corner width. s = across flats.

Related

Compatible products : Black steel pipes · Black cast iron fittings

Useful guides :

• Make wall shelves with plumbing fittings