API-653 & API-650 Iinterpretation 1

[shehzad305]

Appreciate your response on below;


API STANDARD 653

FOURTH EDITION, APRIL 2009

ADDENDUM 1, AUGUST 2010

ADDENDUM 2, JANUARY 2012

ADDENDUM 3, NOVEMBER 2013

9.2.4.6 states;

If a door sheet cut line crosses a [highlight #FCE94F]lap-welded[/highlight] or a riveted [highlight #FCE94F]horizontal seam[/highlight], the placement assembly shall be constructed of two separate plates, with the lower section butt- welded to the adjacent shell course by means of full penetration, full fusion vertical welds. The upper section shall be lapped over or under the lower section and the upper plate shall be butt welded to the existing shell plate. After the butt welds are completed, the horizontal lap shall be fillet welded along both inside and outside edges.


From this paragraph it seems that Lap weld could be there for horizontal seams of shell course.

But API-650 12th Ed. March 2013 (5.1.5.3) didn't talk about lap welds for horizontal seams.


It seems this is a conflict between 653 & 650.....how will you interpret this??

 

[fegenbush]

The answer is simple. API previously allowed lap welded horizontal seams. API 653 must, by the very nature of the standard, take into account repairs of design details which are no longer permitted in new construction. Another example of this is the fact that API no longer supports API 12A (riveted tanks), but the tanks still exist and must be inspected and maintained.

 

[IFRs]

As Mr. Fegenbuch stated:

API 650 is for new tanks and does not allow lap welded shell plate.
See section 5.1.3.4 "Single-welded lap joints are permissible only on bottom plates and roof plates."

API 653 includes inspection and repair of existing tanks and lap and riveted tank shells are out there in quantity.