×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Eccentric reducers Inside bore dimensions

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

RE: Eccentric reducers Inside bore dimensions

Hey...

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

Hello sree60,

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

(OP)
Hi John

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

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources