Re: [PipingDesign] How is Tensile Strength Established by Tube Spec?

From: <M.>
Date: Mon Jan 14 2008 - 15:52:00 EST

Per Para. 323.1.2 of ASME B31.3, unlisted materials may be used if "they confirm to a published specification covering chemistry, physical and mechanical properties, method and process of manufacture, heat treatment, and quality control". This requirement shall be satisfied if the selected material is in accordance with some published standard such as an ASTM or non US standards such as Deutsches Institute fur Normung e.V (DIN)standards. Please refer to ASME B31.3 Para. 302.3 & Para. 323.2.4 B too this regard

Khaled Mahmoud
Jeddah Refinery

> On Jan 14, 2008, at 12:38 PM, Ken Nisly-Nagele
> wrote:
> > I'm working with an unlisted B31.3 material for a
> tubing spec. I
> > want to
> > determine the allowable stress for the flexibility
> analysis.
> You need to use a listed material with
> B31.[anything], and you've
> discovered the reason why. Materials used for code
> purposes require
> that the minimum mechanical properties and
> weldability be established
> or the structural design would be invalid. There are
> ways around it,
> but they require that properties be established by
> testing. In your
> case the 1016 material probably doesn't have a
> reliable yield point
> because of variations in manufacture or thermal
> treatment. If it were
> me, I'd say no-go--use something permitted by the
> Code.
> If you're doing some kind of design analysis, you
> can use Machinery's
> Handbook to get typical properties and reduce them
> by at least 15%
> and run the calculations, but that won't make the
> design conform to
> B31.3. I've been asked to pretend that I were rating
> an existing
> design to find the 'Code' pressure, and I don't
> proceed until my
> client realizes that it's not going to be a
> Code-equivalent vessel
> with Code design margins--and that the exercise has
> all the value of
> putting lipstick on a pig.
> Christopher Wright P.E. |"They couldn't hit an
> elephant at
> | this distance" (last words
> of Gen.
> .......................................| John
> Sedgwick, Spotsylvania
> 1864)
Received on Mon Jan 14 15:52:00 2008

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