1
Revise A.1.1 as shown bold in italics.
Correct A.8.1 and A.9 Editorially.
AGENDA ITEM 650-557
A.1.1 This appendix provides requirements
Sheet 1 of 3
Date: Sept.30, 2002
for field-erected tanks of relatively small
capacity in which the stressed components
have a maximum nominal thickness of 12.5 Title: Appendix-A, Flush Type Clean outs. Para.
A.1.1, A.8.2 Conflict.
mm (1/2 in.), including any corrosion
allowance specified by the purchaser. The
Source: B. Mistry’s letter of May 17, 2002
stressed components include the shell and
Hello Bob and Phil,
reinforcing plates, bottom and shell
Recently, I had the need to study Flush Type
reinforcing plates for flush-type cleanout
clean out requirements in Appendix-A tank and
fittings and flush-type connections, and
I discovered some conflict in Para. A.1.1 and
bottom plates that are welded to the shell.
A.8.1, A.8.2.
but the stressed components do not
include, other bottom plates, covers, and
Para. A.1.1 limits all stress components
nozzle and manhole necks and their
including components of flush type clean out
assembly to 1/2". In other words, no
flanges. Maximum nominal thickness of
components in flush type clean out can exceed
12.5mm (1/2”) does not apply to bottom
1/2". Para. A.8.2 allows flush type cleat out
plates not welded to the shell, bottom
upto 5/8"thick without post weld treatment. It
reinforcing plate of flush type clean outs
means that, Appendix-A tank can have flush
and flush type shell fittings, flanges and
type clean out with 5/8" stress components
without PWHT. This conflicts with 1/2"
cover plate of flush type clean outs, nozzle
thickness limitation in A.1.1.
and manholes necks, their flanges and
cover plates.
A.8.1 The details and dimensions of flush-type
cleanout fittings shall conform to 3.7.7, Figures
3-9 and 3-10, and Tables 3-11 3-9 through
3-13 3-11.
A.8.2 The provisions for stress relief specified
in 3.7.4 and 3.7.7.3 are not required unless they
are specified by the purchaser or unless any
plate in the unit has a thickness greater than 16
mm (5/8 in.).
A.9 Flush-Type Shell Connections
The details and dimensions of flush-type shell
connections shall conform to 3.7.8, Figure 311, and Table 3-11 3-12.
A.9.1 The provisions for stress relief specified
in 3.7.4 and 3.7.8.3 are not required unless
they are specified by the purchaser or unless
any plate in the unit has a thickness greater
than 16 mm (5/8 in.).
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It is quite possible that allowing 5/8" thickness for
flush type clean out was deliberate. In earlier
edition of API-650, shell plate and reinforcing
plate containing flush type clean out had to be at
least 1/16" thicker but not to exceed 1/8". This
requirement was eliminated not too long ago. In
earlier edition, Appendix-A tank with 1/2" thick
shell had to have shell and reinforcing plate,
containing flush type clean out , thicker than .5".
Reviewing Table 3-10 of API-650, 1/2"
thickness limit on bottom reinforcing plate
will limit clean out size to 24"x24" with shell
height of 34' 0". This is quite restrictive.
Allowing 5/8" thickness, one can have 24"x24"
clean out in a tank upto 53' 0" high.
I suggest that we revise Para. A.1.1 to allow
5/8" thick components in Flush Type clean outs
in Appendix-A tanks.
There is also Editorial correction required in
A.8.1. Tables 3-11 through 3-13 should read
Tables 3-9 through 3-11. In A.9, Table 3-14
should read Table 3-12.
2
AGENDA ITEM 650-557
Sheet 2 of 3
Date: Sept.30, 2002
Further research of past Edition revealed the
following.
Appendix-A (as we know) , included in recent
Edition of API-650 did not exist prior to 7 th.
Edition of API-650. What we call Appendix-A now
was the Basic Tank Design, with stress values
limited to 21000 psi.
(1) API-650, 1964
Maximum size of clean out 48"x48".
PWHT required if any component exceeds
5/8".
(2) API-650, 1966, 1970,1973,1978
No change.
(3) API-650, 1980- 1988, 7Th. Edition
Appendix-A , as we know, is introduced .
Stress Components were restricted to 1/2". Flush
Type components were excluded from 1/2"
limitations.. PWHT is required if components
exceeded 5/8".
(4)API-650 1988, 8Th. Edition.
Appendix-A restricts 1/2" to all stress
components including Flush Type Clean out,
as in current edition. However, it permits 5/8"
components in flush type components without
PWHT. In other words, contradiction in AppendixA has been around since 8Th. Edition of API-650.
Purpose:
Correct and resolve conflict in para. A.1.1 and
A.8.2. Permit components in Flush Type Clean
outs over ½”. Clarify that flush type clean out with
components not exceeding 5/8” can be used in
Appendix-A tank without PWHT and over 5/8”
thick can be used with PWHT.
D:\116108285.docPage 2 of 3
3
AGENDA ITEM 650-557
Sheet 3 of 3
Contact:
Bhana Mistry
TIW Steel Platework
Tel: 905-684-9421
Fax: 905-684-7310
Email: bmistry@tiwsteelplatework.ca
Technical Justification:
Same as stated in Purpose above.
Cost Effects:
None.
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