TUBE-PLUMBING WITH –AN TUBE NUTS AND TUBE SLEEVES (Part 1)

TUBE-PLUMBING WITH –AN TUBE NUTS AND TUBE SLEEVES

by Mike Mavrigian

photos by author

an02

If hard lines are preferred to flexible hose, but you want to connect using AN 37-degree seating/sealing, you’ll use tube nuts and tube flares on metal tubing. The hard line (steel, aluminum or stainless steel) must be flared, using a 37-degree flaring tool. A tube sleeve slips on immediately behind the flare. This tube sleeve features a concave seat that mates to the back side of the tube flare. Behind the tube sleeve is a tube nut. This draws the tube sleeve and the flare onto the tube to the male 37-degree AN fitting or adapter.

When making tube assemblies, first slip the tube nut over the unflared tube, followed by the tube sleeve. The tube nut’s threaded port must face the end of the tube that will be flared. The tube sleeve’s smaller O.D. shoulder faces the tube nut, with the larger O.D. sleeve shoulder facing the end of the tube that will be flared.
Once the tube nut and sleeve are in position on the tube, then the tube is flared. Don’t forget to install the tube nut and sleeve onto the tube before flaring (this is a common mistake that many people make).

As far as sizing is concerned, the AN dash size refers to the outside diameter of the tubing.

Hard tubing, equipped with the appropriate size tube nut and sleeve, will allow tubing connection to -3, -4, -6, -8, -10, -12 or -16 male AN fittings/adapters. This hard tubing plumbing may be used for any plumbing application where the flexibility of hose is not required. Examples are plumbing fuel and nitrous oxide from the engine-mounted distribution block to the nitrous oxide injectors; or plumbing a fuel line from an engine-mounted fuel pump to the carburetor. If any movement is anticipated between the two points, use a flexible hose plumbing system instead. For example, never run a hard line from a chassis-mounted location to the engine as engine rock will require plumbing flex.

In some cases, hard tubes are chosen for appearance, where a street rodder has decided that clean hard line plumbing will best complete the visual theme of the build. If the application calls for hard-line plumbing, the use of -AN tube nut/sleeve assemblies provide a secure and leak-proof connection, as opposed to connecting a hard line to a nipple fitting with a short piece of rubber hose and a hose clamp. It also looks much more professional

chart12

an03Hard-line plumbing isn’t relegated to small diameter tubes only. Notice the curved -12 tube that serves as a water feed at the cylinder head and the 90-degree scavenge tube at the front of the rocker cover.

diagram
Tube nuts are used in conjunction with tube sleeves on metal tubing that features a 37 degree flare. This allows a secure sealing connection to -AN male fittings/adapters.
(Illustration courtesy Russell Performance 18-194)

an04

Granted, this example has nothing to do with plumbing fluid, but for this street rod engine, I decided to run the spark plug wires inside 3/8-inch aluminum tubing, feeding them through the base of the air cleaner housing using tube nuts and sleeves, with the nuts attaching to a series of -6 to 1/4-inch NPT adapters.

Tags: , ,




  • http://www.plumbingoakland.org Oakland Plumbing

    O man. this is crazy! Exclusively for show car only, with this piping it will easily overheat in a matter of time. Love the chrome though, good job on this one guys!

    -Francis

  • Dmack

    nigga that shit is gay fuck u

  • Dmack

    shut up bitch

  • http://www.bes.co.uk plumbing

    Great resource,I enjoy reading your post because I learn many things that I can use with my project which seems a good alternative.

  • http://oakland.mrdrain.com/plumbing.php Oakland Plumbing

    Great resource.I can see your blog picture that are provided a diffent types of car seating you’ll use tube nuts.

  • http://piedmont.mrdrain.com/plumbing.php plumbing Piedmont

     Thanks for taking this opportunity to discuss  this, I
    feel  fervently  about this and I like about this subject.  If
    possible, as you gain information, please update  this blog with more
    information for all visitor .  I have found it really useful.

  • http://piedmont.mrdrain.com/plumbing.php plumbing Piedmont

     Thanks for taking this opportunity to discuss  this, I
    feel  fervently  about this and I like about this subject.  If
    possible, as you gain information, please update  this blog with more
    information for all visitor .  I have found it really useful.