Jayl13

Hey guys few questions to the metal workers and welders on this site.

with the Offshore headers, the tube inside a tube, are they bent at the same time with a mandrel bender or are they bent separately and then some how assembled and welded to the flange and the collector or collar?

Anyone have any information on this at all?
basically in a nut shell, how to they make these things?

Thanks
Jason

cobra marty

I think both. Some tubes are bent separately and then inserted into each other and others are bent together-- fill the two tubes with packed sand and then bend them together.

Jayl13

Sand?
That is the secret?
SAND?

are there like metal fingers or fins if you will on the inside tube to the outside tube?
How do you keep the inside tube from touching the outside tube on this deal?

Thanks CM

Jason

cobra marty

Yea, put one tube inside the other and then fill the inside and the area between the tubes with sand and keep the inner tube centered, pack it in and then bend and then shake it out. Weld the ends at the flanges and they stay separate, not touching.

Vinny P

It sounds to me that the process of using sand can make for some mistakes here and there. What if the tubes touch in the bend somewhere? Wouldn't that cause a bad hotspot and possible crack in the pipe? I guess that the manufactureres would say that they have this procedure perfected but mistakes can happen.

Mbam

Actually, both methods are used. The material between the tubes is a low melting point metal alloy. Cerrobend rings a bell. It melts well below the boiling point of water. CMI pieces their headers together with nuclear quality welds. Hot spots are a concern with either method. Even though they might be concentric when cold the pipes move a lot when they warm up.

Jayl13

Would a coil spring be a better buffer between the pipes and then just pull it out when your done?
Do these companies use TIG or MIG welding techniques for their
stuff?
I see CMI has this cool collar thing at the base that the one pipe is welded to the inner pipe after it comes off the block flange and starts its sweep up, Do all companies do this or is it just CMI that
allows that about 1-2 inches of bare metal be heated and rest is cooled by the water jacket?

Just interested in how these things are made and produced and why the hell they are 3500 a pair is all

Saw monster garage last night so Now I feel I can make a pair
Tim Allen Oh yeah yeah yeah RRRRRRRRRRRRRRR

Jason

ragtop409

Jay I think this would be a good challange for you over the winter sence some one else will be fix'in your motors Charlie

Jayl13

Well the thought had crossed my mind about making headers for the boat but also as a business more or less.
Start up capital is what is going to probably kill this whole idea since pipe benders (mandrel benders to be more specific) are very costly and welding supplies and office and work space and storage space to hold the completed ones type of thing will cost a small fortune)
But ya never know.
My dry exhaust setup that I built worked out flawlessly for the little time I was out on the water with the baja.
That is incentive to produce some cool stuff I would think.
Maybe a CNC machine and make my own custom risers would be an idea too but just as a thought.
(dont know how long aluminum would hold up)
but be assured, if it comes from me, Ill warranty the damn things for 10 years and I wont chop your nuts off with price either.
Stellings 3500 a pair
Yeah you wait until I get some of this market
your going DOWN!
Jason

ragtop409

Jay I new you had dry pipes but did not know you made them yourself tell us about them lets see a picture.
I think aluminum would hold up ok sence that is what the hp manifolds are made out of and Stainless Marine's entry leval risers are aluminum.