Hi,Please refer UG 81 for tolerance for formed heads. Find the extraction below.UG-81 TOLERANCE FOR FORMED HEADS
(a)
The inner surface of a torispherical, toriconical,hemispherical, or ellipsoidal head shall not deviate outside
of the specified shape by more than 1
1⁄4% of D nor insidethe specified shape by more than
5⁄8% of D, where D is thenominal inside diameter of the vessel shell at point of
attachment. Such deviations shall be measured perpendicular
to the specified shape and shall not be abrupt. The
knuckle radius shall not be less than that specified.
(b)
Hemispherical heads or any spherical portion of atorispherical or ellipsoidal head designed for external pressure
shall, in addition to satisfying (a) above, meet the
tolerances specified for spheres in UG-80(b) using a value
of 0.5 for
L/Do.(c)
Measurements for determining the deviations specifiedin (a) above shall be taken from the surface of the
base metal and not from welds.
(d)
The skirts of heads shall be sufficiently true to roundso that the difference between the maximum and minimum
inside diameters shall not exceed 1% of the nominal
diameter.
(e)
When the skirt of any unstayed formed head ismachined to make a driving fit into or over a shell, the
thickness shall not be reduced to less than 90% of that
required for a blank head (see UW-13) or the thickness of
the shell at the point of attachment. When so machined,
the transition from the machined thickness to the original
thickness of the head shall not be abrupt but shall be tapered
for a distance of at least three times the difference between
the thicknesses.
Thanks & regards,(karthik)Karthikeyan.SQA/QC ManagerGetabec Energy Co.,Ltd.379,Moo6,Soi8,Nikhomphatana,Rayong-21180,Thailand.Phone: 0066 38 897035-8 (Off)Fax: 0066 38 897034Hand Phone: 0066 892512282
--- On Thu, 10/21/10, vijay panchal <panchalvijay001@gmail.com> wrote:
From: vijay panchal <panchalvijay001@gmail.com>
Subject: Re: [MW:7687] Beginning to SA-450 meaning
To: materials-welding@googlegroups.com, limesh78@gmail.com
Date: Thursday, October 21, 2010, 12:40 PM
PLS can u tell me that how much overcrowing is permissible in 2:1 ellispodial dishend and trospherical and in section vii Where to refer
pls its urgent i need u r help
thanks
vijay
On Tue, Oct 19, 2010 at 7:14 PM, limesh M <limesh78@gmail.com> wrote:
--Dear All,I found that,Beginning to SA-450 on the front page of ASME BPV SEC II Part A 2010 Edition.What it means?Regards,Limesh
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