The art of making a leak-proof connection with hydraulic couplings is to tighten the couplings properly at the time of installation. An overtightened coupling may be just as apt to leak as an under tightened coupling. This is because over-tightening a coupling may result in overstressing and/or cracking. The torque values in the following table give minimum and maximum torque recommendations. The minimum value will create a leakproof seal under most conditions. Applying torque values greater than the maximum recommendation will distort and/or crack the fitting.

Coupling and Adapter Torque Recommendation

For 37° & 45° (Machined or Flared)

Size		Steel				Brass
		Ft. Lbs.		Newton-Meters		Ft. Lbs.		Newton-Meters
Dash	Inches	Min	Max	Min	Max	Min	Max	Min	Max
-4	1/4	10	11	13	15	5	6	6-3/4	9
-5	5/16	13	15	18	20	7	9	10	13
-6	3/8	17	19	23	26	12	15	17	20
-8	1/2	34	38	47	52	20	24	27-2/3	33
-10	5/8	50	56	69	76	34	40	46-1/3	55
-12	3/4	70	78	96	106	53	60	72-1/3	82
-16	1	94	104	127	141	74	82	100-1/2	111
-20	1-1/4	124	138	169	188	75	83	101-1/2	113
-24	1-1/2	156	173	212	235	79	87	107	118
-32	2	219	243	296	329	158	175	214	237

For Flat-Face O-Ring Seal (Steel)

Size		Newton-Meters
Dash	Inches	Min	Max
-4	1/4	14	16
-6	3/8	24	27
-8	1/2	43	54
-10	5/8	60	75
-12	3/4	90	110
-14	7/8	90	110
-16	1	125	240
-20	1-1/4	170	190
-24	1-1/2	200	245

For SAE O-Ring Boss (Steel)

Size		Ft.Lbs. Working  Pressures 4,000 psi (27.5 Mpa) and below		Newton-Meters Working Pressures 4,000 psi (27.5 Mpa) and below		Ft.Lbs. Working Pressures Above 4,000 psi (27.5  Mpa)		Newton-Meters  Working Pressures Above 4,000 psi (27.5  Mpa)
Dash	Inches	Min	Max	Min	Max	Min	Max	Min	Max
-3	3/16	–	–	–	–	8	10	11	13
-4	1/4	14	16	20	22	14	16	20	22
-5	5/16	–	–	–	–	18	20	24	27
-6	3/8	24	26	33	35	24	26	33	35
-8	1/2	37	44	50	60	50	60	68	78
-10	5/8	50	60	68	81	72	80	98	110
-12	3/4	75	83	101-1/2	113	125	135	170	183
-14	7/8	–	–	–	–	160	180	215	245
-16	1	111	125	150	170	200	220	270	300
-20	1-1/4	133	152	180	206	210	280	285	380
-24	1-1/2	156	184	212	250	270	360	370	490

For BSP 30° Inverted Cone

Size		Ft.-Lbs.		Newton-Meters
Dash	Inches	Min	Max	Min	Max
-2	1/8	7	9	9	12
-4	1/4	11	18	15	24
-6	3/8	19	28	26	38
-8	1/2	30	36	41	49
-10	5/8	37	44	50	60
-12	3/4	50	60	68	81
-16	1	79	95	107	129
-20	1-1/4	127	152	172	206
-24	1-1/2	167	190	226	258
-32	2	262	314	355	426

For DIN 2353 12°, 30°  and Universal Inverted Cone

Size		Ft.-Lbs.		Newton-Metres
Light Series Tube O.D. (mm)	Heavy Series Tube O.D. (mm)	Min	Max	Min	Max
-6	—	7	15	10	20
-8	—	15	26	20	35
-10	-8	18	30	25	40
-12	-10	22	33	30	45
-14	-12	26	37	35	50
-15	-14	30	52	40	70
—	-16	30	52	40	70
-18	—	44	74	60	100
-22	-20	59	89	80	120
-28	-25	74	111	100	150
—	-30	74	162	150	220
-35	—	133	184	180	250
-42	-38	148	221	200	300

Maximum Recommended Torque for Dry NPTF (Tapered) Pipe Threads

Size	Ft-Lbs.	Newton-Meters
-2	20	25