cleaning welds in stainless steel

[chunkolini]

I have heard lots of versions of what you can and cant do to clean up welds on stainless. A few to follow

'Dont grind it, it will go rusty' really?
'have dedicated discs for grinding it as they get contaminated with mild steel and leave contamination' that sounds reasonable.

'Dont use flap wheels' why not?

'only use dedicated stainless steel wire brushes' that sounds ok.

'You have to remove the oxide layer of the welds as this leads to rust streaks.' Is this the case? On the monster Triffid this could be a hassle as the weds are all concealed inside the structure. See image below, the whole thing is being covered in scales with concealed welds.


Any info gratefully recieved.

I am mostly after cleaning the welds rather than grinding them to oblivion, but I have a couple that need to be hidden.

Chunko'.

 

[Bullyterrier]

pickling paste

 

[chunkolini]

I have got a small pot of that, but there are also a few that need some grinding. Also do the welds concealed inside the thing need treating or not?
Chunko'.

 

[English Steve]

Also do the welds concealed inside the thing need treating or not?

I wouldn't think so if you used stainless wire.

 

[Bullyterrier]

I think you are supposed to treat all stainless welds with it arnt you? Stops them from rusting and removes the heat colouring. I think it leaves them matt, so if you want it shiney you will need to polish them after.

 

[Bullyterrier]

While on the pickling paste, does anyone know if it works for removing heat colouring on welds on mild steel not stainless?

 

[madkayaker]

Whats pickling paste?

 

[Bullyterrier]

a gel or paste that you brush or spray on that cleans and or passifies the weld in stainless

 

[madkayaker]

I see nothing for me to worry bout then

 

[Bullyterrier]

Taken from another website:
Why Pickle?
Pickling cleans and restores the corrosion resistance of components fabricated from Stainless Steel and thus considerably influences their service life and usefulness.

The corrosion resistance of Stainless Steels is primarily based upon the presence of at least 13% chromium in the alloy. In combination with oxygen, the chromium forms a dense chemically resistance passive layer of chromic oxide which protects the surface against corrosion.

Unfortunately, every mechanical treatment will damage the surface layer by contamination with ferritic matter, changes to the microstructure, development of stresses and a reduction of chromium content. In addition, any heat treatment, such as annealing and welding, will lead to scaling and discolouration. These aspects not only diminish the visual appearance of the component, but in particular reduce its corrosion resistance.

A dense passive layer of chromium oxide can only form on a metallically pure surface.

Professionally pickled Stainless Steel surfaces and welding seams:

# are metallically pure, free of scale and discolouration
# have full corrosion resistance
# have a decorative satin metallic appearance.

 

[runnach]

I thought pickling paste was either banned or close to it? It is horrible stuff to work with, if there is a bare part of skin, paste will find and nip the skin like hell.

Is there not an electrical equivalent available now??

 

[gavuk]

Still have paste at work and the local welding supplies,used to use flap disc on stainless gaurds,but we polished afterwards with a mop never saw any ill effects,hope tis helps.Gav

 

[TechnicAl]

Chunko
I havent read it all but I think this should answer a lot of your questions
http://www.bssa.org.uk/topics.php?sub_category=75

Havent we been through this before (somewhere else)

 

[dannyweld]

I thought pickling paste was either banned or close to it? It is horrible stuff to work with, if there is a bare part of skin, paste will find and nip the skin like hell.

Is there not an electrical equivalent available now??

it stings the hell out if you get in the eyes, i,m always useing the stuff, even managed to get some on my c##k last year (dont ask). their is an electrical version, the fronius magic wave does it,
you can pick the paste up in most welder suppliers i'd say. stainless steel suppliers usually stock it as well. best to use a soft brush to apply it.

 

[simon718]

danny gonna hafta ask....

 

[chunkolini]

Hi all
Al I lost the original thread and there seems to be so many opinions, the article you linked to has helped, if grinding it use dedicated discs.
Pickling paste, I have used it a couple of times. Which idiot snifed the white fume coming off it? Narrsty
Danny was removing his makeup with it.

Still not clear regards having to remove the oxide layer on the concealed welds.

Keep them coming.

chunko'.

Chunko'.

 

[dannyweld]

my fly was open and i was'nt wearing any underpants, simple as that, thats why i use a soft brush, they give you a hard brush with the pickle but i find it flicks the stuff around. was looking at your work chunko, dont let the pickle near the mild unless you want the rust look, big time. after you pickle leave for about 40 minutes, damp weather is the best time to do it, never leave in direct sunlight, power wash off, clean with celluose tinners, then rub with scotch bright, in the end of the day you cant beat a bit of elbow grease for bringing up the shine.

 

[dannyweld]

and here is an example of HR tube and plate after coming into contact with the pickle

 

[Bullyterrier]

So Danny,
Pickling paste will rust mild. I have been wondering if I could use it on some of the small stuff I make instead of flapp disking to remove the bluing..

 

[Bullyterrier]

You posted the same time as I was writing