Eccentric reducers Inside bore dimensions
Eccentric reducers Inside bore dimensions
(OP)
Dear members
We have a situation where a supplier has given 3x2 INCH eccentric reducer sch XXS.
( Dimensions to conform to ASME B 36.10 Material Low alloy ASTM A 234-Gr 4130)
The bore at the reduced end is 38 mm which confirms to requirements as per dimensional standard.However if u look through the 2 IN bore of the reducer one can notice a reduction in the inside bore. When measured, the inside bore is less to a tune of 8 mm ( 30mm) where the inside bore surface starts to take a transition towards 3 in.
Is there any dimensional standard which addresses the inside bore dimensions at various locations especially at transition points along the reducer length?
If one has to reject the reducers what will be the basis
of rejection?
Any help would be greatly appreciated.
Regards
Sree60
We have a situation where a supplier has given 3x2 INCH eccentric reducer sch XXS.
( Dimensions to conform to ASME B 36.10 Material Low alloy ASTM A 234-Gr 4130)
The bore at the reduced end is 38 mm which confirms to requirements as per dimensional standard.However if u look through the 2 IN bore of the reducer one can notice a reduction in the inside bore. When measured, the inside bore is less to a tune of 8 mm ( 30mm) where the inside bore surface starts to take a transition towards 3 in.
Is there any dimensional standard which addresses the inside bore dimensions at various locations especially at transition points along the reducer length?
If one has to reject the reducers what will be the basis
of rejection?
Any help would be greatly appreciated.
Regards
Sree60





RE: Eccentric reducers Inside bore dimensions
Tube of this type is generally know as nominal bore and as such the bore diameter can deviate although 8mm under size is very excessive.
1 to 2mm is more usual. It is probably a manufacturing fault.
You should return the reducer to the supplier and get a replacement, unless you can live with the reduced bore size.
Regards
Adrian
RE: Eccentric reducers Inside bore dimensions
What standard was the reducer manufactured to? What standard does your procurement contract specify for welding fittings?
The B16.9 Standard for welding fittings does not specify the exact geometry for the fittings and it does not specify the wall thickness for the fittings. The end-to-end dimensions, center-to-end (where applicable) and "squareness" are specified only (also the wall thickness at the weld lines must match the pipe). The Standard specifies that the fitting "can be shown to be able to pass a burst test". From a practical standpoint that means that if you weld a 3X2 XXS reducer to matching straight pieces of NPS 2 and NPS 3 XXS pipe and cap the ends with B16.9 welding pipe caps and then pressurize the assembly to destruction the straight pipe will burst before the fittings burst. The wall thickness and geometry of the reducer is up to the manufacturer to design as long as it complies with the B16.9 end-to-end dimensions and the ends are bored to match the wall thickness of the matching pipe and it will pass the burst test.
Not really too much in the way of other dimensions is "standard".
Regards, John.
RE: Eccentric reducers Inside bore dimensions
Thanks for the insight. clause 6.2.2 of ASME 16.9
states that bore diameters away from ends are not specified.
If special flow path requirements are needed the bore dimensions shall be specified by the purchaser.
This probably answers my question
Thanks guys for ur time
sree60