Stainless Steel Flu Pipe.

[rusty69]

It's that time of year that I need to replace the flu pipe on our Morso squirrel. I don't know if the smokeless we have been burning has contributed to its early demise, but it has only lasted 5 winters before holes have started to appear.

Before I go out and buy the standard mild steel pipe I have always used, is there any reason not to go with a stainless steel pipe? I think it's 4.5" outer diameter, and a straight flu pipe.

Silly questions:

1. Does the grade of stainless matter?

2. Do I go for the same thickness as I would with a mild steel pipe, or will 1.5 mm suffice?

3. WIll any additional weight of a stainless pipe be a problem?

4. Can I paint it black like Mick Jagger?

5. Anyone recommend a supplier?

6. Will cutting it to length be a problem?

Thanks.

[Tracy D'arth]

1 no   2 yes , yes  3 no  4 yes  5 no  6 no

[rusty69]

2 minutes ago, Tracy D'arth said:

1 no   2 yes , yes  3 no  4 yes  5 no  6 no

You forgot 7. Can I use the exhaust pipe advertised on ebay? 

 

https://www.ebay.co.uk/itm/255148823671?

Edited August 26, 2023 by rusty69

[Alan de Enfield]

17 minutes ago, rusty69 said:

1. Does the grade of stainless matter?

2. Do I go for the same thickness as I would with a mild steel pipe, or will 1.5 mm suffice?

3. WIll any additional weight of a stainless pipe be a problem?

4. Can I paint it black like Mick Jagger?

5. Anyone recommend a supplier?

6. Will cutting it to length be a problem?

 

 

Loads of suppliers - one on ebay : Premium Stainless Steel Flue Pipe for Wood Stove Efficient and Long lasting | eBay

 

Ours (on the pipsqueak) was stainless.

It was comparatively very thin, but lasted many years.

Being thin more radiant heat seemed to transfer to the cabin

SS is more expensive than mild steel (or even old drain pipe)

 

 

Edited August 26, 2023 by Alan de Enfield

[blackrose]

I don't think you need a stainless flue pipe. You just need a decent wall thickness mild steel pipe. Mine is 5mm but 4mm is good.

 

How thick was the one that rotted through? I think a 4mm mild steel pipe will last longer than a 1.5mm stainless pipe. Just look at those thin "traditional" stainless steel chimneys that narrow boaters seem to love and have to replace on a regular basis.

Edited August 26, 2023 by blackrose

[rusty69]

11 minutes ago, Alan de Enfield said:

 

 

Loads of suppliers - one on ebay : Premium Stainless Steel Flue Pipe for Wood Stove Efficient and Long lasting | eBay

 

Ours (on the pipsqueak) was stainless.

It was comparatively very thin, but lasted many years.

Being thin more radiant heat seemed to transfer to the cabin

SS is more expensive than mild steel (or even old drain pipe)

 

 

Thanks for the link. I'm thinking it might be preferable to have no join in the pipe. 

2 minutes ago, blackrose said:

I don't think you need a stainless flue pipe. You just need a decent wall thickness mild steel pipe. Mine is 5mm but 4mm is good.

 

How thick was the one that rotted through? I think a 4mm mild steel pipe will last longer than a 1.5mm stainless pipe. Just look at those thin "traditional" stainless steel chimneys that narrow boaters seems to love and have to replace on a regular basis.

I don't know how thick the current one is, I think it was a midland chandlers one. I suspect maybe 2-2.5 mm. I hadn't thought about going thicker. Would the additional weight be a problem? Bearing in mind the Morso squirrel top plate is delicate at the best of times. 

 

Perhaps fixing the pipe at the deck collar and have it floating at the stove collar could alleviate some of the problem. 

[Tonka]

17 minutes ago, Alan de Enfield said:

 

 

Loads of suppliers - one on ebay : Premium Stainless Steel Flue Pipe for Wood Stove Efficient and Long lasting | eBay

 

 

 

 

That link is for pipe for wood stoves. 

The op might have a multi fuel stove

 

[rusty69]

4 minutes ago, Tonka said:

That link is for pipe for wood stoves. 

The op might have a multi fuel stove

 

Yes, it's a morso squirrel multi fuel stove. I forget the number. 

[blackrose]

My last (3mm thick) mild steel flue pipe was installed in 2006 and I removed it last year only because I wanted to try to improve the stove draw with a slightly larger diameter pipe. It still looked fine and I gave it to someone nearby fitting out their boat.

[rusty69]

2 minutes ago, blackrose said:

My last (3mm thick) mild steel flue pipe was installed in 2006 and I removed it last year only because I wanted to try to improve the stove draw with a slightly larger diameter pipe. It still looked fine and I gave it to someone nearby fitting out their boat.

Our previous pipes had also lasted well. Perhaps 12 years or more. I suspect the change in the fuel over the last couple of years may be the problem. We had a backboiler that failed after a couple of years use too, so it's not just the flu. 

 

Maybe we need to reconsider what we have been burning. 

[MtB]

18 minutes ago, rusty69 said:

I don't know how thick the current one is, I think it was a midland chandlers one. I suspect maybe 2-2.5 mm.

 

The (several) flue pipes I've bought from Midland Chandeliers over the years have all been 3mm wall thickness. Very light.

 

The proper cast iron flues (ISTR) we had in yester-century were about 1/4" wall thickness. Or they might have been drain pipes. 

 

 

 

 

 

[rusty69]

1 minute ago, MtB said:

 

The (several) flue pipes I've bought from Midland Chandeliers over the years have all been 3mm wall thickness. Very light.

 

The proper cast iron flues (ISTR) we had in yester-century were about 1/4" wall thickness. Or they might have been drain pipes. 

 

 

 

 

 

I have heard of people using cast iron drain pipe, but again, the weight issue worries me. Perhaps unduly. 

I suppose the other option is a flexible SS flu liner. 

Edited August 26, 2023 by rusty69

[MtB]

1 minute ago, rusty69 said:

I have heard of people using cast iron drain pipe, but again, the weight issue worries me. Perhaps unduly. 

 

You missed my tortured puns! 

 

I agree about the weight, one of my Squirrel tops cracked as a result of the weight of the cast iron flue resting on it, I reckon. 

 

 

[Tonka]

3 minutes ago, rusty69 said:

I have heard of people using cast iron drain pipe, but again, the weight issue worries me. Perhaps unduly. 

I suppose the other option is a flexible SS flu liner. 

I have never liked the idea of a flexible flu liner as I feel the tar could build up in the crinkles and eventually cause a fire

[rusty69]

1 minute ago, Tonka said:

I have never liked the idea of a flexible flu liner as I feel the tar could build up in the crinkles and eventually cause a fire

Hmmm. I hadn't thought of that, thanks. 

3 minutes ago, MtB said:

You missed my tortured puns

Sorry bout that. 

[MtB]

3 minutes ago, rusty69 said:

Sorry bout that. 

 

Apology accepted, I guess you're feeling a bit under the weather because of your flu. 

 

 

[rusty69]

1 minute ago, MtB said:

 

Apology accepted, I guess you're feeling a bit under the weather because of your flu. 

 

 

That flew right over my head. 

Dear @Jen-in-Wellies please could you change the thread title to include the word flue or flew, but not necessarily remove the word flu so I don't have to have endure any more cruel jokes about my poor smelling.

 

Thank you. 

 

I would of course do it myself but I'm far too lazy. 

 

PS where did Athy go, has he been kidnapped? 

[MtB]

14 minutes ago, rusty69 said:

PS where did Athy go, has he been kidnapped? 

 

I think he's come to his senses, and don't moderate no moar. 

 

[dave moore]

1 hour ago, blackrose said:

I don't think you need a stainless flue pipe. You just need a decent wall thickness mild steel pipe. Mine is 5mm but 4mm is good.

How thick was the one that rotted through? I think a 4mm mild steel pipe will last longer than a 1.5mm stainless pipe. Just look at those thin "traditional" stainless steel chimneys that narrow boaters seem to love and have to replace on a regular basis.

 

Our traditional chimney was made by Dave Parrot in stainless steel, double skinned, in 2000. It is still with the boat today.

[magnetman]

I've got a 1.5mm thick 304 stainless flue on one of my fires.  Its a one-off fire and we Tig welded a 76mm 316 elbow on the back as the flue outlet into which is dropped two 1m long swaged sections of 70mm exhaust pipe. I've done one winter with the magic fire burning wood no problems and light it most days in fact it is alight right now burning some maple as I just got soaked in a rain storm. 

 

Works fine no sign of corrosion damage and because of a lack of internal corrosion the flue itself stays cleaner. No little rusty surfaces for the smoke and soot to grab onto

 

On the other boat the fire also has a stainless flue pipe (80mm) which has been there since the boat was built about 35 yars ago. I have had 3 winters of regular use on that mainly burning smokes less coal (brazier) no flue problems and I doubt there will be.

 

I think 316 is better than 304 for a number of different reasons. 

 

 

Get swaged fittings so you can take the whole thing apart easily. 

 

 

70mm stainless flue using swaged exhaust 304 ss pipe in 1m lengths. 

 

 

 

[rusty69]

5 minutes ago, magnetman said:

I've got a 1.5mm thick 304 stainless flue on one of my fires.  Its a one-off fire and we Tig welded a 76mm 316 elbow on the back as the flue outlet into which is dropped two 1m long swaged sections of 70mm exhaust pipe. I've done one winter with the magic fire burning wood no problems and light it most days in fact it is alight right now burning some maple as I just got soaked in a rain storm. 

 

Works fine no sign of corrosion damage and because of a lack of internal corrosion the flue itself stays cleaner. No little rusty surfaces for the smoke and soot to grab onto

 

On the other boat the fire also has a stainless flue pipe (80mm) which has been there since the boat was built about 35 yars ago. I have had 3 winters of regular use on that mainly burning smokes less coal (brazier) no flue problems and I doubt there will be.

 

I think 316 is better than 304 for a number of different reasons. 

 

 

Get swaged fittings so you can take the whole thing apart easily. 

 

 

70mm stainless flue using swaged exhaust 304 ss pipe in 1m lengths. 

 

 

 

That's a thing of beauty. 

 

Do you think 1.5-2 mm will be OK? 

[magnetman]

1.5mm seems fine to me. I can't really see any problem with it. 

 

I would marginally prefer 316 to 304 but I'm not convinced it makes all that much difference. A nice thing with having two parts to the flue is one can remove it, clean and internally inspect the pipes. 

 

I know it is a bit awkward with the collar etc but I just put a round silicone pan handling thing on the outside with a small round hole. Stretched over the pipe the silicone thing covers all of the collar and no rain gets in at all. 

[Jen-in-Wellies]

9 hours ago, rusty69 said:

is there any reason not to go with a stainless steel pipe?

Thanks for asking the question. I am also interested in the answers. Being based close to where stainless steel was invented, why not use it?

 

8 hours ago, rusty69 said:

Dear @Jen-in-Wellies please could you change the thread title to include the word flue or flew, but not necessarily remove the word flu so I don't have to have endure any more cruel jokes about my poor smelling.

 

No can do. The post has gone viral with the current words. 😀

 

[rusty69]

3 minutes ago, magnetman said:

1.5mm seems fine to me. I can't really see any problem with it. 

 

I would marginally prefer 316 to 304 but I'm not convinced it makes all that much difference. A nice thing with having two parts to the flue is one can remove it, clean and internally inspect the pipes. 

 

I know it is a bit awkward with the collar etc but I just put a round silicone pan handling thing on the outside with a small round hole. Stretched over the pipe the silicone thing covers all of the collar and no rain gets in at all. 

Sounds intriguing, what's a silicone pan handling thing, if I may be so bold to ask? Does this then not neccesitate messing about with silicone goo and fire rope? 

Edited August 26, 2023 by rusty69
Remove, a, stray, comma,

[magnetman]

Silicone pan handling thing