Difficulty with clad header boxes
Difficulty with clad header boxes
(OP)
I have tried specifying alloy clad header boxes for air coolers, but have received resistance to doing that. I have asked why this cannot be done, but have not understood the constraints. Can someone with fabrication experience explain why would it be so difficult to weld clad plate to form a clad header box? I always thought that the root pass could be easily made with enough alloy filler to avoid dilution with subsequent passes made with carbon steel.
Being able to use clad plate instead of carbon steel would greatly reduce the cost of the exchanger.
Being able to use clad plate instead of carbon steel would greatly reduce the cost of the exchanger.





RE: Difficulty with clad header boxes
Your suggestion is quite valid and is done routinely. Roll or explosive bond, sheet or weld cladding applications on plate material is done to reduce material costs by providing the same corrosion resistance results as if using a solid plate of the corrosion resistant alloy (CRA). The only possible exception I could think of to shy away from cladding are physical or geometrical constraints of the object.
RE: Difficulty with clad header boxes
Also do you have a plugsheet? What do you do with it, overlay inside the holes before tapping?
Having recently checked clad plate prices, it is not necessarily cheaper than solid 304 for example, although you don't say what your alloy is. Lead times are forever.
Maybe further question your vendors to see what the concerns are?
Regards,
Mike
RE: Difficulty with clad header boxes
Clad plate was also hard to get in small quantities when I worked for a fabricator. Only exception was when a large clad vessel was being constructed, you could order more by increasing the size or number of plates on the larger order.
Main justification for clad is the stability (valve slide plates, where solid stainless would distort on final grinding) or vessels where the higher allowable stresses of the carbon steel backing allow a thinner wall tha solid SS.
RE: Difficulty with clad header boxes
How many nozzles do you have? Lots of little sensor couplings?
Some materials require "clean" forming equipment,if it is a "steel shop" this will be a problem.
I have also seen clad material separate when formed. Cost?
Have not had the problem with the explosive bonded. But sometimes size limited and you need to trim away the outside edges after the blast.
So this along with the welding is a problem.
How much do you wish to pay?
RE: Difficulty with clad header boxes
The only way to properly do welding of these header boxes is if their construction is not plug box but cover plate type.
Manufacturers will resist doing clad construction and quote only solid SS boxes for plug type headers.