JIC Fittings Guide › JIC Torque Specs

JIC Fitting Torque Specs and Assembly Guide

Most JIC leaks come from incorrect assembly: under-tightened nuts that never seat, or over-tightened flares that crack or deform. This page gives typical torque ranges published for steel 37° flare fittings, explains the flats-from-wrench-resistance (FFWR) method many manufacturers prefer, and lists common assembly mistakes. Values here are typical ranges for reference only — always use the torque values published by the manufacturer of your fittings. Sizes are in the main JIC fittings guide.

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Typical Torque Ranges (Steel, 37° Flare)

Dash	Thread	Typical torque (ft-lb)	Typical torque (N·m)
-4	7/16-20	11–12	15–16
-5	1/2-20	15–16	20–22
-6	9/16-18	18–20	24–27
-8	3/4-16	38–42	52–57
-10	7/8-14	57–62	77–84
-12	1-1/16-12	79–87	107–118
-16	1-5/16-12	108–113	146–153
-20	1-5/8-12	127–133	172–180
-24	1-7/8-12	158–167	214–226
-32	2-1/2-12	245–258	332–350

These are typical published ranges for zinc-plated carbon steel fittings with lightly lubricated threads. Torque values vary between manufacturers, plating and materials; stainless steel and brass are commonly assembled to different values. Treat this table as a sanity check, not a specification.

The Flats From Wrench Resistance (FFWR) Method

Torque readings are affected by plating, lubrication and thread condition, so many manufacturers recommend turning the nut a set number of hex flats past the point of first resistance instead:

Align the tube or hose with the fitting so the flare sits squarely on the cone without side load.
Run the nut down finger-tight until it bottoms on the seat.
Tighten with a wrench until you feel firm resistance (wrench resistance). Mark a line across the nut and the fitting body.
Turn the nut the number of flats specified by the manufacturer (typically one to two flats for small and mid sizes, fewer for large sizes), using the mark to count.
Back up the fitting body with a second wrench so you do not twist the tube or hose.

Common Assembly Mistakes

Using sealant or tape. JIC seals on the flare; sealant does not help and can contaminate the system.
Over-torquing a leaking joint. If a correctly torqued joint leaks, the flare or seat is usually damaged. Inspect and replace rather than tightening further.
Misalignment. A tube pulled into place by the nut will not seat evenly.
Mixed seat angles. A 45° or 24° part on a 37° seat will not seal at any torque — see JIC vs SAE 45° flare.
Re-using damaged parts. Inspect flares for nicks, scratches and cracks before reassembly.

Port ends (ORB, NPT, BSPP) on adapters have their own assembly procedures and torque values; follow the manufacturer's data for each end. See JIC fitting types guide and JIC materials and pressure ratings.

FAQ

What is the torque for a -8 JIC fitting?

Typical published values for steel -8 JIC (3/4-16) are around 38–42 ft-lb (about 52–57 N·m). Always use your fitting manufacturer's value.

Should I use torque or flats?

Many manufacturers recommend the flats-from-wrench-resistance method because it is less affected by plating and lubrication. Follow whichever method your manufacturer specifies.

Do JIC fittings need thread sealant?

No. JIC seals metal-to-metal on the 37° flare. Do not use tape or pipe dope.

Why does my JIC fitting still leak after tightening?

Common causes are a damaged or cracked flare, mismatched seat angles, misalignment or debris on the seat. Over-tightening usually makes it worse.

Are stainless JIC torque values the same as steel?

Not necessarily. Stainless and brass fittings are often assembled to different values; check the manufacturer's data.

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