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# What effect does heat have on deflection of valve blade

## What effect does heat have on deflection of valve blade

(OP)
We are manufacturing a valve from a rectangular stainless steel (310)plate 1700 mm x 2150 mm. The deflection of the 20 mm thick plate at normal temp. is 1,9 mm. if the air flow temp is 900 deg C what iffect will this have on the deflection. Is there a way of calculating this effect.

### RE: What effect does heat have on deflection of valve blade

Sure there is.
I presume that you know the load, or can figure it out from the existing info.
And that the stresses are well below yield.
Then just use the modulus at the desired temp and re-calc.

Check for creap limits while you are at it.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.
http://www.trent-tube.com/contact/Tech_Assist.cfm

### RE: What effect does heat have on deflection of valve blade

(OP)
I managed to find a site http://www.sandmeyersteel.com/310-310S.html which gives the following info

Density lbm/in3 g/cm3
at 68°F (20°C) 0.29
8.03
Coefficient of Thermal Expansion (min/in)•°F (mm/m)•°K
at 68 - 212°F
(20 - 100°C) 8.8 15.9
at 68 - 932°F
(20 - 500°C) 9.5 17.1
at 68 - 1832°F
(20 - 1000°C) 10.5 18.9
Electrical Resistivity mW•in mW•cm
at 68°F (20°C) 30.7 78.0
at 1200°F (648°C) -- --
Thermal Conductivity Btu/hr•ft•°F W/m•K
at 68 - 212°F
(20 - 100°C) 8.0 13.8
at 68 - 932°F
(20 - 500°C) 10.8 18.7
Specific Heat Btu/lbm•°F J/kg•K
at 32 - 212°F
(0 - 100°C) 0.12 502
Magnetic Permeability (annealed)1
at 200H 1.02
Modulus of Elasticity (annealed)2 psi GPa
in tension (E) 29 x 106
200
in shear (G) 11.2 x 106 77

### RE: What effect does heat have on deflection of valve blade

You can use this data.
E at room temp is 29Mpsi
and at 900C let's call it 18.5Mpsi

Assume that the part is a beam, use the room temp properties to calculate the load required to cause hte room temp defection.
The use the high temp E to calculate the new defection.
If your stress is above about 5,000psi then you will have creep at 900C and the parts will defect too much and eventually fail from it.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.
http://www.trent-tube.com/contact/Tech_Assist.cfm

### RE: What effect does heat have on deflection of valve blade

(OP)
I have used formulae from R.J.Roark & W.C. Young
I have assumed simply supported edges. These are the results
Plate size = 2,15 x 1700 x 16 (5/8") thick
Working pressure = 50 mm WG = 0,0710476 lb/sq. inch
Deflection = .01246" = 0,3 mm
Max stress = 307 lb/sq. inch
Creep/Expansion in 2,15 meter directio = 35 mm
used 2,15 M x(900-20)x 18,9 is this result possible

### RE: What effect does heat have on deflection of valve blade

Another thing which is very hard to predict is distortion caused by uneven heating.  In many high temperature dampers we see distortion/weld failures due to one side being hot and the other side much cooler.  Stainless steels like 310 expand significantly upon heat up to 950C and this uneven expansion can create some significant stresses in the material.  Insulating the cold side or other ways to minimize the temperature differences side to side will help reduce distortion during service.

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