Q What are the limitations of TEMA Mechanical Standard?
Ans. (As per RCB 1.11)
The TEMA Mechanical Std. are applicable to shell and tube heat exchangers, which do not exceed any on the following criteria :-
1) Inside Diameter of 100”(2540mm) inches
2) Product of nominal diameter(inch) and design pressure(psi) of 100000 psi.
3) Design pressure of 3000 psi.
Q What will be the corrosion allowance of part partition plate, when tube side corrosion allowance of a shell & tube heat exchanger is 3mm?
Ans.: Nil, irrespective of Tube Side
(as per RCB 1.518). C.A.
Q As per TEMA, What is the allowable tolerance for Tube sheets & Girth Flange thicknesses?
Q What is the Tube sheet ligament?
Ans.: It is the shortest distance between adjacent tube holes in the tube pattern.
Q What is the max. distance between tube bend and nearest baffle/support Plate in a U -tube heat exchanger?
Ans. : (RCB 4.54) The sum of the bend diameter plus the straight lengths
measured along both the legs from supports to bend tangents does not
exceed the max. unsupported span determined as per Table RCB 4.52
Q What is the minimum pass partition gasket width as per TEMA?
Ans. As per RCB-6.4
For nominal shell diameter less than 23” (584mm)-6.4mm
For Nominal diameter above 23” (584mm)-9.4mm
Q What is the max. ovality at the tube bends of U-Tubes?
Ans: Max. ovality at the tube bends shall not exceed 5% of the nominal dia.
Q In an expanded Tube to tube sheet joint, four grooves are required.Tube sheet material is C.S with SS cladding. As per TEMA where should be the location of grooves?
Ans.: As per RB 7.44 all the four grooves should be in base material i.e. CS part
of tube sheet.
Q In a horizontal Heat Exchangers tube ends are extended 3mm beyond tube sheet face. How much tube ends are extended in vertical exchangers ?
Ans.: It is flushed with tube sheet faces to facilitate complete drainage.
Q What is the formula for calculating min. part partition thickness as per TEMA?
Ans. : t = bsqrt(qB/1.5x S) - RCB 9.132,
‘,b= Plate Dimension –mm
B=Value from table corresponding to a & b
‘q= Pressure Drop across plate in –kPa
S= Code Allowable material stress value- kPa
Q What is TEMA recommended limit for channel cover deflection ?
Ans.: As per TEMA RCB 9.21:
0.8 mm for nominal dia. Through 24”
0.125% of Nominal dia. (Nominal dia./800) for larger size.
Q How much chloride content in ppm in water for hydrotesting of SS & High Nickel alloy vessel is allowed as per our standard pecification?
Ans: 30 PPM
Q What is the thinning percentage value of tube wall thickness after rolling?
Ans. Thinning percentage value of tube wall thickness after rolling shall be in the range from 8% to 12% for CS & 5% to 8% for SS.
Q What is the minimum tube pitch as per IBR?
Ans. As per clause No.580 ===
Tube Pitch (inch) =Tube OD+ Tube Hole dia. + 0.5’’
Q What is the minimum carbon steel baffle thickness as per our standard specification for shell & tube heat exchanger?
Ans. As per clause No.8.4.1, Minimum thickness = 2 x CA