TR5 crack in rear spring mount.

[wimpus]

Yesterday helped a friend getting his rear suspension apart on his TR5 PI.

Found a crack in the right rear top spring mount

Ive heard and welded up the stress cracks on TR250/TR5/TR6's on the front suspension previously.

But cant find any of the rear top spring mount..

 

So.. how to best weld this up ? 

 

 

[Peter Truman]

Is that next to a weld so could the weld affected the steel metalurgy causing the fracture.

we had a 68 inch mild steel pipe operating at around 120psi which literally pulled circumferentially apart 3 in behind the welded joint our pipe guru’s said the steel had crystallised due to the welding stress’s it had lasted over 20 years! 20klm of main had to be drained as it was at the lowest point thankfully no residential properties damaged only a Metro Park we refilled their lake!

[PeteH]

I would be concerned at the apparent gap on the leading edge of the crack?. It suggests that the actual mounting has moved upwards? and possibly twisted?. The alignment I would suggest needs to be checked and the gap pulled back to "but", before any attempt to weld.

It`s not unusual for a failure next to a weld, in what is refered to as the "heat affected zone" (HAZ) where the material has degraded due to heat, often as result of poor welding technique. As this is a spring mount it is also a High stress area subject to repeated cycles. 

My (personal) thoughts are it needs to be welded, once pulled back into alignment, by someone with plenty of experience, even possibly plated to support the weld in the future. I would also be tempted to have the other (oposite) weld subjected to NDT? to rule out stress cracking on that.

Heat affected Zone:-  formed between the melted metal and the unaffected base metal called the heat affected zone (HAZ). In this zone, the metal is not melted but the heat has led to changes in the metal’s micro-structure. These changes in structure can reduce the metal’s strength.

Pete

 

[PeteH]

8 hours ago, Peter Truman said:

Is that next to a weld so could the weld affected the steel metalurgy causing the fracture.

we had a 68 inch mild steel pipe operating at around 120psi which literally pulled circumferentially apart 3 in behind the welded joint our pipe guru’s said the steel had crystallised due to the welding stress’s it had lasted over 20 years! 20klm of main had to be drained as it was at the lowest point thankfully no residential properties damaged only a Metro Park we refilled their lake!

 

Mid 90`s. I receive a call at 6am from my line manager with the message a Laundry in Plymouth, would I speak to them. Called to be told “Our Boiler has got steam coming from the back under the covering”. Ok, shut it down and get the pressure off, start to remove the lagging and I’ll be with you in a couple of hours. On arrival, the lagging removed and there was clearly a crack in the back of the boiler shell from which steam was still issuing. When measured it was over 60” in length adjacent to the shell/back plate seam. This was subsequently put down to failure in the heat affected zone compounded by frequent cycling from 0 to 260psi. They where in the habit of shutting the boiler down between shifts and/or when demand was low. As this plant had been operating at 260psi. They where lucky that the whole backend had not just let go. Had it done, half the laundry would have gone with it!. The Laundry manager actually asked me if they could still run it, as they couldn’t work without it!!. My thoughts where unprintable, I just handed him a Form F90 "cease and desist", and faxed the report to the H&SE!.

Pete

 

 

[Peter Truman]

PeteH , my dad's Aus subsidiary of a NE of England Co in the mid 50's were building a Petro Chem Plant here and were testing a new very large Pressure vessel proir to commissioning when it exploded, unfortunately killing a close family friend (NE Englander), don't know what the OHS outcome was, but I remember all the info re the tank construction X Raying of the welds test procedure etc being on our dining room table for sending to Work Cover to go thro, I remember the X Ray pile as a 10 yr old as I had a broken arm at the time (roller skates). 

I assume the test pressure would have been 30 to 50 % over working pressure? with blow off valve tied down.

[PeteH]

8 hours ago, Peter Truman said:

PeteH , my dad's Aus subsidiary of a NE of England Co in the mid 50's were building a Petro Chem Plant here and were testing a new very large Pressure vessel proir to commissioning when it exploded, unfortunately killing a close family friend (NE Englander), don't know what the OHS outcome was, but I remember all the info re the tank construction X Raying of the welds test procedure etc being on our dining room table for sending to Work Cover to go thro, I remember the X Ray pile as a 10 yr old as I had a broken arm at the time (roller skates). 

I assume the test pressure would have been 30 to 50 % over working pressure? with blow off valve tied down.

This type of fail, is rare especially under test conditions, usually conducted by using water pressure, (SWP+10%) where even a rupture would see a virtual instant drop in pressure and little chance of explosion?. It would suggest they where testing with a Gas (Air?) which would have much more stored energy, and is rarely if ever recomended nor used.

There was a fail on a Babcox Boiler under pre comisoning test, at Cockensie Power station, sometime back in the 70`s, and subsequently I had my first lesson in X ray checking using the films from that repair. The boiler went into service after a long and expensive repair operation and was still certified when the station closed in (I think) the early 2000`s?.

Pete

[Peter Truman]

I was only 10 or 11 so don’t know background and it was 1956 it made the Aus new TV News.

we had a construction engineer forced on us in water operations who instructed a reservoir caretaker to open a cross connection between a 850 AHD supply into a 600 AHD supply zone/system the very experienced caretaker asked the duty Eng do you really want to do this it’s high pressure there could be issues, Yes was the answer, Royce the caretaker I’m doing this under instruction, BANG 6 pipes 20 foot long 900mm dia of lock bar steel pipes split open with 400mld flow going down the street back along the pipe track to the nearest water course  which flooded and damaged several properties incl our MD’s. The Eng was transferred to a desk job in HO in the Chief Eng’s dept! This one couldn’t be blamed on “Act of God” our usual get out of jail excuse.

The final cost of the pipe replacement road repair and private damage was $0.75M like Dr’s we bury our mistakes!

[johny]

23 hours ago, wimpus said:

Yesterday helped a friend getting his rear suspension apart on his TR5 PI.

Found a crack in the right rear top spring mount

Ive heard and welded up the stress cracks on TR250/TR5/TR6's on the front suspension previously.

But cant find any of the rear top spring mount..

So.. how to best weld this up ? 

Apparently this is quite a common failure point and apart from welding the crack itself a reinforcing plate is made up to weld in place across the complete rear side of that suspension girder. Makes sense as thats exactly where the upward force from the springs is concentrated but of course looks like a body off job....

[PeteH]

This is what you are looking at:-

You will need to devise a method of drawing the cracked ends together, before welding or it will be permanently out of alignment.

Pete.

[wimpus]

2 hours ago, PeteH said:

This is what you are looking at:-

You will need to devise a method of drawing the cracked ends together, before welding or it will be permanently out of alignment.

Pete.

Ok.

Will measure it all up and see.

But will weld a piece of metal outside the chassis, so its stronger then before.

Space is tight.

But think there is just enough space to do it.

It will be a job for after christmas !

[Bfg]

It is a common fault on these IRS chassis, but not so very serious - because a spring seat doesn't need to be absolutely accurate. After all it's a flexible spring that sits in a rubber vibration-isolating collar which loosely fits into that seat.   

Although possibly caused by a lack of bump stop at some time,  I suspect it has cracked through repetitive fatigue over the years and the hardening or disintegration / failure of its rubber vibration collar. I might be misreading it, but your photo suggests the cracked flange has sprung outwards...And that the spring seat has not pushed upwards very much at all. 

I'd recommend you thoroughly clean into the corner and into the crack, then just pull the sprung metal back into line and weld it up within that inside corner ..but then reinforce the spring hanger with a triangular plate front and back so as to distribute the loads to further down the chassis' tower..

This < here > is my TR4A chassis, showing the reinforcement I suggest.

Best regards,

Pete