[Nick Flint Posts: 5070 Status: Offline]

QUITE a few things there Ian that I didn't know.
Its always good to know (what you DIDNT know)!
I have a "slight tendency"-------- (large)
to slide inexorably towards the abyss  that is "WWAI" 


I didn't know that 316 fatigues more easily, so JUST IN TIME my new exhausts (that I propose to order and start in hours)
WILL NOW BE 304 DUE TO- cost, fatigue, ease of cutting and welding. Thanks Ian. (phew)


Again Ian, "GOOD ENOUGH" is indeed just THAT.
There is a tattoo parlour in town that will print this on my hands for quite a reasonable fee, tho
im not convinced of their needle hygiene ATM.
A touch of Hep B is not going to be well received----


My KingFisher build was based on the premise of Just what can be achieved if the best is used.
BOY did I pay the price for THAT exercise?
Yes is the answer, heavily.


For those of you still catching up with acronyms----- WWAI stands for --- (in my strange little world) as------
"Whilst We're At It----"

[Ronnie L Posts: 531 Status: Offline]

Ian


That isn’t ranting.
That is good advice, common sense and things as they really are.
Sometimes when you are pondering about things ( which I often do)
These little snippets of wisdom can give you the “light bulb moment” that really helps.
Someone else’s thoughts or “rubbing heads” as my mate calls it, are great.

[Ian Brooks Posts: 3598 Status: Offline]

Hi

Engineering is an interesting subject. You might think it's about doing the very best you can, and all my new Engineers come out of Uni thinking that. The first thing I have to do is reverse all the academic training they've had - which was, in the main, that only their very best would do. Out there in the real world, we don't want the very best. Instead, we want good enough. It must meet its specification and then cost no more than that. We can't sell the very best, because no-one can afford it - nor would they want to. If it's good enough, stop.

So 316 does have better corrosion resistance than 304. It will maintain a bright shiny finish in a hot chlorine rich environment (as long as it hasn't been bent, worked or welded). 304 will also withstand a hot chlorine rich environment such as a hovercraft exhaust but it will go dull.  It will not corrode though - even after 5 years it'll be ok. Notwithstanding earlier comments on welding.

What kills stainless exhausts on a hovercraft is vibration. Stainless is less good in fatigue, and 316 is worse than 304 in this respect. 316 is more expensive of course, and much harder to work with, further adding to the expense. 304 is good enough in corrosion, better in fatigue, cheaper and easier to work, which is why I use it for all my exhausts. Time spent reducing exhaust vibration, on the other hand, is worth every minute.

Sorry - rantings of an Engineer!!!

Ian

[Nick Flint Posts: 5070 Status: Offline]

 

[Warby Posts: 1045 Status: Offline]

But it does say 316 is a Marine Grade SS

[Nick Flint Posts: 5070 Status: Offline]

I NEVER knew that SS became more magnetic when "deformed".
Yep 316 IS best but it doesn't say on this article.
Thanks guys

[tomtilley Posts: 569 Status: Offline]

I use grade 316  stainless steel which is a marine grade  not the 304 grade 316 it is more  expensive but worth it in the long run . Tom

[edwadee Posts: 160 Status: Online เรารักในหลวง]

I have just replaced the flexi on my van after a little over 2 years.
Completely rotted out. Was allegedly stainless.
Always use the clamp on one (as per your pic ) then its realy easy to
change and not too expensive. Also easier to line up.
It's just annoying they rust out so quick.
 

[Warby Posts: 1045 Status: Offline]

Some reading for you Nick
https://www.australwright.com.au/stainless-steel-magnetism-corrosion-resistance/
From a sunny Porthmadog!!

[Philip Posts: 2444 Status: Offline 12" above the Earth's surface WWW]

I've used those, not sure how "stainless" they are but they lasted very well. Probably the best that's out there and not expensive. When buying have a rummage through the different versions, I found one that could be used with different size pipes and it was cheaper than most others. NExAP was designed not to have flexible exhaust sections thereby eliminating any associated problems.

[Nick Flint Posts: 5070 Status: Offline]

Currently fabricating new Stainless exhausts and wonder whether to use these "stress/vibration damping"
connectors. They are described as Stainless and are "almost" unaffected by magnetism.
Question- Is it reasonable to expect a tiny amount of attraction to a magnet,
OR should the stainless steel be 100% unaffected by nearby magnet?