Agenda Item 650-218
Title:
Cleanup of Footnote Issues
Date:
January 6, 2015
Revision:
0
Handled By:
Ingrid Pederson
Enbridge Pipelines Inc.
10201 Jasper Ave
Edmonton, AB T5J 3N7
Telephone: 780-420-8522
Mobile: 780-266-5796
Email: ingrid.pederson@enbridge.com
_________________________________________________________________________________________
_
Purpose:
This item is to clean up footnotes contained in API 650, including any required renumbering,
using proper formatting as per API Document Format and Style Manual, and removing
technical information from footnotes and incorporating into the body of the standard
Source:
Doug Miller’s email of August 7, 2014
Impact:
None
Discussion:
Regarding the footnotes in API 650, some numbering corrections are required. There are
also a few that contain technical requirements that should be moved into the appropriate
paragraphs.
Rules from API Document Format and Style Manual:
Section 6.7.1, d) footnotes:
These elements shall not contain requirements or any other information
indispensable for the use of the document.
Section 6.7.5 Footnotes:
Footnotes to the text give additional information; their use shall be kept to a
minimum. A footnote shall not contain requirements or any information
considered indispensable for the use of the document.
_________________________________________________________________________
Proposed Changes: Format of ballot is to give the original text and footnote, and then proposed revision
with all technical footnotes incorporated into the text. Changed/added text is in purple.
Footnote #22 (page 138, 5-88)
Original Text:
5.10.2.6 Frangible Roof: A roof is considered frangible (see 5.8.5 for emergency venting requirement) if the
roof-to-shell joint will fail prior to the shell-to-bottom joint in the event of excessive internal pressure. When a
Purchaser specifies a tank with a frangible roof, the tank design shall comply with a, b, c, or d, of the following:
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a) For tanks 15 m (50 ft) in diameter or greater, the tank shall meet all of the following.
1) The slope of the roof at the top angle attachment does not exceed 2:12.
2) The roof support members shall not be attached to the roof plate.
3) The roof is attached to the top angle with a single continuous fillet weld on the top side (only) that does
not
exceed 5 mm (3/16 in.). No underside welding of roof to top angle (including seal welding) is permitted.
4) The roof-to-top angle compression ring is limited to details a through e in Figure F-2.
5) All members in the region of the roof-to-shell joint, including insulation rings, are considered as
contributing to the roof-to-shell joint cross-sectional area (A) and this area is less than the limit shown
below:
NOTE The terms for this equation are defined in Annex F.
The top angle size required by 5.1.5.9.e may be reduced in size if required to meet the cross sectional area limit.
b) For self-anchored tanks with a diameter greater than or equal to 9 m (30 ft) but less than 15 m (50 ft), the
tank shall meet all of the following.
1) The tank height is 9 m (30 ft) or greater.
2) The tank shall meet the requirements of 5.10.2.6.a.2-5.
3) The slope of the roof at the top angle attachment does not exceed 3/4:12.
4) Attachments (including nozzles and manholes) to the tank shall be designed to accommodate at least
100 mm (4 in.) of vertical shell movement without rupture.
5) The bottom is butt-welded.
c) Alternately, for self-anchored tanks less than 15 m (50 ft) diameter, the tank shall meet all of the following.
1) The tank shall meet the requirements of 5.10.2.6.a.1 through 5.
2) An elastic analysis22 shall be performed to confirm the shell to bottom joint strength is at least 1.5 times
the top joint strength with the tank empty and 2.5 times the top joint strength with the tank full.
3) Attachments (including nozzles and manholes) to the tank shall be designed to accommodate at least
100 mm (4 in.) of vertical shell movement without rupture.
4) The bottom is butt-welded.
d) For anchored tanks of any diameter, the tank shall meet the requirements of 5.10.2.6.a and the anchorage
and counterweight shall be designed for 3 times the failure pressure calculated by F.6 as specified in 5.12.
22 A
frangible roof satisfies the emergency venting requirement for tanks exposed to fire outside the tank. See API 2000.
Frangible roofs are not intended to provide emergency venting for other circumstances such as a fire inside the tank, utility
failures, chemical reactions, or overfill. See API Publication 937 and API Publication 937-A.
Proposed revision:
5.10.2.6 Frangible Roof: A roof is considered frangible (see 5.8.5 for emergency venting requirement) if the
roof-to-shell joint will fail prior to the shell-to-bottom joint in the event of excessive internal pressure. A frangible
roof satisfies the emergency venting requirement for tanks exposed to fire outside the tank. See API 2000.
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Frangible roofs are not intended to provide emergency venting for other circumstances such as a fire inside the
tank, utility failures, chemical reactions, or overfill. See API Publication 937 and API Publication 937-A. When
a Purchaser specifies a tank with a frangible roof, the tank design shall comply with a, b, c, or d, of the
following:
a) For tanks 15 m (50 ft) in diameter or greater, the tank shall meet all of the following.
1) The slope of the roof at the top angle attachment does not exceed 2:12.
2) The roof support members shall not be attached to the roof plate.
3) The roof is attached to the top angle with a single continuous fillet weld on the top side (only) that does
not
exceed 5 mm (3/16 in.). No underside welding of roof to top angle (including seal welding) is permitted.
4) The roof-to-top angle compression ring is limited to details a through e in Figure F-2.
5) All members in the region of the roof-to-shell joint, including insulation rings, are considered as
contributing to the roof-to-shell joint cross-sectional area (A) and this area is less than the limit shown
below:
NOTE The terms for this equation are defined in Annex F.
The top angle size required by 5.1.5.9.e may be reduced in size if required to meet the cross sectional area limit.
b) For self-anchored tanks with a diameter greater than or equal to 9 m (30 ft) but less than 15 m (50 ft), the
tank shall meet all of the following.
1) The tank height is 9 m (30 ft) or greater.
2) The tank shall meet the requirements of 5.10.2.6.a.2-5.
3) The slope of the roof at the top angle attachment does not exceed 3/4:12.
4) Attachments (including nozzles and manholes) to the tank shall be designed to accommodate at least
100 mm (4 in.) of vertical shell movement without rupture.
5) The bottom is butt-welded.
c) Alternately, for self-anchored tanks less than 15 m (50 ft) diameter, the tank shall meet all of the following.
1) The tank shall meet the requirements of 5.10.2.6.a.1 through 5.
2) An elastic analysis22 shall be performed to confirm the shell to bottom joint strength is at least 1.5 times
the top joint strength with the tank empty and 2.5 times the top joint strength with the tank full.
3) Attachments (including nozzles and manholes) to the tank shall be designed to accommodate at least
100 mm (4 in.) of vertical shell movement without rupture.
4) The bottom is butt-welded.
d) For anchored tanks of any diameter, the tank shall meet the requirements of 5.10.2.6.a and the anchorage
and counterweight shall be designed for 3 times the failure pressure calculated by F.6 as specified in 5.12.
Footnotes #26 to #29 (page 323, H-1)
Original Text:
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H.2 Types of Internal Floating Roofs
H.2.1 The internal floating roof type shall be selected by the Purchaser after consideration of both proposed
and future product service, operating conditions, maintenance requirements, regulatory compliance, service
life expectancy, ambient temperature, maximum design temperature, product vapor pressure, corrosion
conditions and other compatibility factors. Other operating conditions requiring consideration include (but are
not limited to) anticipated pumping rates, roof landing cycles, and the potential for turbulence resulting from
upsets, such as vapor slugs injected into the tank. Safety and risk factors associated with the roof types shall
also be evaluated.26 The type of roof, which shall be designated by the Purchaser on the Data Sheet, Line 30,
shall be one of the types described in H.2.2.
H.2.2 The following types of internal floating roofs are described in this Annex.
a) Metallic pan internal floating roofs 27,28,29 have a peripheral rim above the liquid for buoyancy. These roofs
are in full contact with the liquid surface and are typically constructed of steel.
b) Metallic open-top bulk-headed internal floating roofs 26,27 have peripheral open-top bulk-headed
compartments for buoyancy. Distributed open-top bulk-headed compartments shall be used as required.
These roofs are in full contact with the liquid surface and are typically constructed of steel.
c) Metallic pontoon internal floating roofs have peripheral closed-top bulk-headed compartments for buoyancy.
Distributed closed-top bulk-headed compartments shall be used as required. These roofs are in full contact
with the liquid surface and are typically constructed of steel.
d) Metallic double-deck internal floating roofs have continuous closed top and bottom decks, which contain
bulkheaded compartments for buoyancy. These roofs are in full contact with the liquid surface and are typically
constructed of steel.
e) Metallic internal floating roofs on floats have their deck above the liquid, supported by closed pontoon
compartments for buoyancy. These roof decks are not in full contact with the liquid surface and are typically
constructed of aluminum alloys or stainless steel.
f) Metallic sandwich-panel/composite internal floating roofs have metallic or composite material panel modules
for buoyancy compartments. Panel modules may include a honeycomb or closed cell foam core; however, cell
walls within the panel module are not considered “compartments” for purposes of inspection and design
buoyancy requirements (see H.4.1.7 and H.4.2.1).30 These roofs are in full contact with the liquid surface and
are typically constructed of aluminum alloys or Purchaser approved composite materials. 27
g) Hybrid internal floating roofs shall, upon agreement between the Purchaser and the Manufacturer, be a
design combination of roof types described in H.2.2.b and H.2.2.c, having bulkhead compartments with closedtop perimeter pontoon and open-top center compartments for buoyancy. These roofs are in full contact with the
liquid surface and are typically constructed of steel.
h) Other roof materials or designs if specified and described in detail by the Purchaser on the Data Sheet.
26 Internal
floating roof tanks generally have reduced fire risk, and the use of fixed fire suppression systems is often not
mandatory. Various internal floating roof materials will have unique flammability characteristics, melting points and weights
(perhaps with reduced buoyancy being required). If fire suppression systems are used, certain roof types need to be
evaluated for full surface protection. NFPA 11 Standard for Low-Expansion Foam can provide guidance for this evaluation.
27 The Purchaser is cautioned that this design does not have multiple flotation compartments necessary to meet the
requirements of H.4.2.1.3.
28 These designs contain no closed buoyancy compartments, and are subject to flooding during sloshing or during
application of fire-fighting foam/water solution. Also, without bracing of the rim being provided by the pontoon top plate,
design to resist buckling of the rim must be evaluated.
29 If the floating roof is a) a metallic pan roof with or without bulkheads, or b) a non-metallic roof with or without closed
buoyancy compartments, then the tank is considered a fixed-roof tank (i.e., having no internal floating roof) for the
requirements of NFPA 30. See NFPA 30 for spacing restrictions on floating roof tanks.
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30 A
single inspection opening per panel module is permitted, regardless of core material; however, core materials
producing enclosed spaces within a module may result in undetectable combustible gas in areas isolated from the
inspection opening.
Design buoyancy shall be based on the loss of any two full panel modules (not cells within modules).
Proposed revision:
H.2 Types of Internal Floating Roofs
H.2.1 The internal floating roof type shall be selected by the Purchaser after consideration of both proposed
and future product service, operating conditions, maintenance requirements, regulatory compliance, service
life expectancy, ambient temperature, maximum design temperature, product vapor pressure, corrosion
conditions and other compatibility factors. Other operating conditions requiring consideration include (but are
not limited to) anticipated pumping rates, roof landing cycles, and the potential for turbulence resulting from
upsets, such as vapor slugs injected into the tank. Safety and risk factors associated with the roof types shall
also be evaluated.26 Internal floating roof tanks generally have reduced fire risk, and the use of fixed fire
suppression systems is often not mandatory. Various internal floating roof materials will have unique
flammability characteristics, melting points and weights (perhaps with reduced buoyancy being required). If fire
suppression systems are used, certain roof types need to be evaluated for full surface protection. NFPA 11
Standard for Low-Expansion Foam can provide guidance for this evaluation. The type of roof, which shall be
designated by the Purchaser on the Data Sheet, Line 30, shall be one of the types described in H.2.2.
H.2.2 The following types of internal floating roofs are described in this Annex The Purchaser is cautioned that
metallic pan, metallic open-top bulk-headed, and metallic sandwich-panel/composite internal floating roof
designs do not have multiple flotation compartments necessary to meet the requirements of H.4.2.1.3.
a) Metallic pan internal floating roofs 27,28,29 have a peripheral rim above the liquid for buoyancy. These roofs
are in full contact with the liquid surface and are typically constructed of steel. These designs contain no
closed buoyancy compartments, and are subject to flooding during sloshing or during application of fire-fighting
foam/water solution. Also, without bracing of the rim being provided by the pontoon top plate, design to resist
buckling of the rim must be evaluated. If the floating roof is a) a metallic pan roof with or without bulkheads, or
b) a non-metallic roof with or without closed buoyancy compartments, then the tank is considered a fixed-roof
tank (i.e., having no internal floating roof) for the requirements of NFPA 30. See NFPA 30 for spacing
restrictions on floating roof tanks.
b) Metallic open-top bulk-headed internal floating roofs 26,27 have peripheral open-top bulk-headed
compartments for buoyancy. Distributed open-top bulk-headed compartments shall be used as required.
These roofs are in full contact with the liquid surface and are typically constructed of steel.
c) Metallic pontoon internal floating roofs have peripheral closed-top bulk-headed compartments for buoyancy.
Distributed closed-top bulk-headed compartments shall be used as required. These roofs are in full contact
with the liquid surface and are typically constructed of steel.
d) Metallic double-deck internal floating roofs have continuous closed top and bottom decks, which contain
bulkheaded compartments for buoyancy. These roofs are in full contact with the liquid surface and are typically
constructed of steel.
e) Metallic internal floating roofs on floats have their deck above the liquid, supported by closed pontoon
compartments for buoyancy. These roof decks are not in full contact with the liquid surface and are typically
constructed of aluminum alloys or stainless steel.
f) Metallic sandwich-panel/composite internal floating roofs have metallic or composite material panel modules
for buoyancy compartments. Panel modules may include a honeycomb or closed cell foam core; however, cell
walls within the panel module are not considered “compartments” for purposes of inspection and design
buoyancy requirements (see H.4.1.7 and H.4.2.1).30 A single inspection opening per panel module is
permitted, regardless of core material; however, core materials producing enclosed spaces within a module
may result in undetectable combustible gas in areas isolated from the inspection opening. Design buoyancy
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shall be based on the loss of any two full panel modules (not cells within modules). These roofs are in full
contact with the liquid surface and are typically constructed of aluminum alloys or Purchaser approved
composite materials.27
g) Hybrid internal floating roofs shall, upon agreement between the Purchaser and the Manufacturer, be a
design combination of roof types described in H.2.2.b and H.2.2.c, having bulkhead compartments with closedtop perimeter pontoon and open-top center compartments for buoyancy. These roofs are in full contact with the
liquid surface and are typically constructed of steel.
h) Other roof materials or designs if specified and described in detail by the Purchaser on the Data Sheet.
Footnote 31 (page 401, M-5)
Informative footnote, leave in and renumber to #22
Footnote 32 (page 436, P-24)
Informative footnote, leave in and renumber to #23
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