High Strength Friction Grip Bolt

Structure Bolts, Nuts and Washers in Friction Grip Joints

The use of high strength structual fasteners in friction grip joints has been one of the most importnat developments in structural engineering over the last four decades. It provides a simple method of transmitting loads through a structural joint by the friction on the contact face developed through the high clamping force from correctly tightened high strength bolts and nuts.

The bolts are fitted in clearnance holes and since the joint is designed to resist slp , they are not subject to bearing or shear forces and thus remain in virtually static tension throughout their working life with fluctuating loads having very little, of any effect on bolt stress.

The head dimensions (across float sizes) of H.S.S. Bolts and Nuts are one step higher than those of the normal hexagon bolts and nuts of the same diameter. The bearing pressure under the head of H.S.S. Bolts will this be necessarily lower than that of the conventional of the hard bolt head into softer structural steel is therefore prevented.

Reliability:

Once tightened, the bolts will remain tight and maintain the permanent strength of the joint. Absence of heavy stress concentration due to absence of bearing between bolts and plates. As bolts are in tension, it does not permit loosening, thus making it most ideal where vibrations are involved.

Economy:

Fewer high strength bolts are required than M.S. bolts and rivets. Drilling of close tolerance holes is not required. Overall weight of the structure will be very light.

Simplicity:

A minimum of skill is required in tightening and the operators need only to follow a few simple rules.

Convenience:

Whether in the workshop or at the site, H.S.S. Bolts enable joints to be made easily. Welding of site splices can be elimnated avoiding the difficulties of welding in adverse weather conditions. Absence of pneumatic hammers used in riveted joints reduce noise level.

Maximum Permissible Applied Forces for Joints as per IS 4000:1992
Nominal Size of Bolt	Stress Area of Bolt in mm²		Maximum Permissible Applied Forces in Bolts in kN
			Tension (P) in Bolts of Preperty Class		Shear in Bearing Type Joints V for Bolts of Property Class
	Shank	Thread	8.8	10.9	8.8		10.9
					Shank	Thread	Shank	THread
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)
M 16	201	157	56.7	78	40.2	31.4	52.3	40.8
M 20	314	245	88.2	122	65.2	50.8	81.6	63.7
M 24	452	353	127	176	93.8	73.2	117	91.8
M 30	706	561	202	280	146	116	148	146
M 36	1017	817	294	407	211	169	264	212

Thread Size		M16	M20	(M22)	M24	(M27)	M30	M36
Pitch		2.0	2.50	2.50	3.00	3.00	3.50	4.00
dw	Max.	16.70	20.84	22.84	24.84	27.84	30.84	37.00
	Min.	15.30	19.16	21.16	23.16	26.16	29.16	35.00
da	Max.	18.70	23.24	25.24	27.64	30.40	33.40	39.40
S	Max.	27.00	34.00	36.00	41.00	46.00	50.00	60.00
	Min.	26.16	33.00	35.00	40.00	45.00	49.00	58.80
E	Min.	29.56	37.29	39.55	45.20	50.85	55.37	66.44
K	Max.	10.75	13.40	14.90	15.90	17.90	19.57	23.55
	Min.	9.25	11.60	13.10	14.10	16.10	17.65	21.45
N	Min.	0.60	0.80	0.80	1.00	1.20	1.20	1.50

Maxumum Recommended Tightening Torque Metric Thread for Quality 8.8
Nominal Thread Dia mm	Course NM	Fine NM
M16	252	268
M18	347	391
M20	492	546
M22	670	736
M24	851	926
M27	935	1344

Mechanical Properties of H.S.S. Bolts
Thread Size	Stress Area	Property Class 8.8			Property Class 10.9
		Ultimate Load (Min)	Proof Load (Min)	Hardness	Ultimate Load (Min)	Proof Load (Min)	Hardness
	mm²	Newtons	Newtons	HRC	Newtons	Newtons	HRC
M16	157	125600	91060	22-32	163280	130310
M20	245	203350	147000	23-34	254800	203350
(M22)	303	251490	181800		315120	251490
M24	353	292990	211800		367120	292990	32-39
(M27)	459	380970	275400		477360	380970
M30	561	465630	336600		583440	465630
M36	817	678110	490200		849680	678110

High Strength Structural Washers:

High Strength Structural Washers - Dimensions
Bolt Size		M16	M20	(M22)	M24	(M27)	M30	M36
d1	Min.	18.00	22.00	24.00	26.00	30.00	33.00	39.00
	Max.	18.43	22.52	24.52	26.52	30.52	33.62	39.62
d2	Max.	34.00	42.00	44.00	50.00	56.00	60.00	72.00
	Min.	32.40	40.40	42.40	48.40	54.10	58.10	70.10
S	Max.	4.60	4.60	4.60	4.60	4.60	4.60	4.60
	Min.	3.10	3.10	3.40	3.40	3.40	3.40	3.40
Weight Kg/1000pcs		20.3	31.3	33.2	44.7	54.8	61.4	89.7

High Strength Structural Nuts:

High Strength Structural Nuts - Dimensions
Thread Size		M16	M20	(M22)	M24	(M27)	M30	M36
Pitch		2.0	2.50	2.50	3.00	3.00	3.50	4.00
W	Max.	27.00	34.00	36.00	41.00	46.00	50.00	60.00
	Min.	26.16	33.00	35.00	40.00	45.00	49.00	58.80
C	Min.	29.56	37.29	39.55	45.20	50.86	55.37	66.44
H	Max.	17.10	20.70	23.60	24.20	27.60	30.70	36.60
	Min.	16.40	19.40	22.30	22.90	26.30	29.10	35.00
Weight Kg/1000pcs		60.4	115.3	142.8	197.7	282.3	365.0	281.8

Mechanical Properties of H.S.S. Nuts
Thread Size	Property Class 8		Property Class 10
	Proof Load	Hardness	Proof Load	Hardness
	Newtons		Newtons
M16	168900	HRB 89 to HRC 38	195500	HRB 26 to HRC 38
M20	263400		305000
(M22)	325700		377200
M24	379500		439500
(M27)	493400		571500
M30	603100		698400
M36	878300		1017200