Thermal fatique failure and mechanical loading at the same time
Thermal fatique failure and mechanical loading at the same time
(OP)
Dear all,
We face an issue with a regenarator vessel, where in two years of operation in an emergency shutdown for other reason we found a crack that is propagating around the knuckle between a grid floor and the join. With the knuckle.
The metal is 304h and the width of the weld is double v 57 width...diameter of grid is 6690
The weld was under refractory.
I would like to share and hear your approaches regarding causes and ways of repairing the grid. I am available for any other information you may need regarding design conditions.
Kind regards
We face an issue with a regenarator vessel, where in two years of operation in an emergency shutdown for other reason we found a crack that is propagating around the knuckle between a grid floor and the join. With the knuckle.
The metal is 304h and the width of the weld is double v 57 width...diameter of grid is 6690
The weld was under refractory.
I would like to share and hear your approaches regarding causes and ways of repairing the grid. I am available for any other information you may need regarding design conditions.
Kind regards





RE: Thermal fatique failure and mechanical loading at the same time
The second part of this is repair and this requires surface NDT to verify removal of the crack before welding, weld repair itself and post repair NDT.
RE: Thermal fatique failure and mechanical loading at the same time
I understand by your post that the crack nucleate at the weld (probably at the weld toe), which is very common. Was the weld toe grinded after welding? This procedure avoids quite a lot crack nucleation in welds.
RE: Thermal fatique failure and mechanical loading at the same time
RE: Thermal fatique failure and mechanical loading at the same time
Thickness of the knuckle is 57 and is covering around 180 deg all over periphery (diameter 6700).crack has went through weld depth, and regarding propagation of crack i hace the opinion that is extending since there is 35 tones on the bed ncluding lining and the vessel cooled-shrickaged.
For the pic i dont have it with me now....In short future..
RE: Thermal fatique failure and mechanical loading at the same time
RE: Thermal fatique failure and mechanical loading at the same time
We were looking for 2 options.
Either Arc gouging only the cracked area and welding, either or lifting the grid by hydraulic snubbers and making bevel and welding afterwards..
RE: Thermal fatique failure and mechanical loading at the same time
RE: Thermal fatique failure and mechanical loading at the same time
RE: Thermal fatique failure and mechanical loading at the same time
A picture/drawing would truly help.