pghu-eh-cspds-000103 rev 0 - design loads for structures

7/30/2019 PGHU-EH-CSPDS-000103 Rev 0 - Design Loads for Structures

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PG-PDS 04-01-03 Design Loads for Structu res October 2008

Esso Highlands Limit ed Strict ly Confidential - For Venture Use Only PGHU-EH-CSPDS-000103

Page 2 of 10 ExxonMobil Development Company Rev 0

Scope

[I] Specification covers the loads for the design of support structures, equipment, and other facilities.

The loads include gravity (dead and live) loads, process-generated loads, wind, and earthquake.


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Table of Contents

1. Required References ..............................................................................................4

1.1. ASCEAmerican Society of Civil Engineers..................................................4

2. Additional References............................................................................................4

2.1. PNG LNG Project Specifications ...................................................................4

2.2. APIAmerican Petroleum Institute.................................................................4

3. Design......................................................................................................................4

3.1. General ..........................................................................................................4

3.2. Live Loads......................................................................................................5

3.3. Wind Loads....................................................................................................5

3.4. Earthquake Loads..........................................................................................6

3.5. Process Loads...............................................................................................6

3.6. Maintenance Loads........................................................................................7

3.7. Construction Loads........................................................................................7

3.8. Other Loads...................................................................................................8

3.9. Load Combinations, Allowable Stresses, and Load Factors .........................8

At tachment: Purpose Codes Defini tions ...................................................................10


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1. Required References

1) [I] This Section lists Codes and Standards that are generically referenced and assumed to be a partof this document. Unless otherwise specified herein, use the latest edition.

1.1. ASCEAmerican Society of Civil Engineers

ASCE 7 Minimum Design Loads for Buildings and Other Structures

"Wind Loads and Anchor Bolt Design for Petrochemical Facilities." 1997. American Society of

Civil Engineers. (ASCE Report# 40262)

Guidelines for Seismic Evaluation and design of Petrochemical Facilities 1997. American

Society of Civil Engineers. (ASCE Report # 40264)

2. Additional References[I] The following Practices and Standards shall be used with this Practice as applicable.

2.1. PNG LNG Project Specifications

PG-PDS 04-01-04 Surge Vibration Design Loads

PG-PDS 04-99-17 Roads and Bridges

2.2. APIAmerican Petroleum Institute

API STD 620 Design and Construction of Large, Welded, Low-Pressure Storage Tanks

API STD 650 Welded Steel Tanks for Oil Storage

3. Design

3.1. General

1) [I] The following basic loads that shall be considered in the structural design include:

a) Dead loads.

b) Live loads.

c) Operating loads including fluid, impact, piping restraint, surge vibration, thermal, andvibration loads.

d) Maintenance loads including bundle pull loads.

e) Environmental loads including earthquake, snow, ice, rain, and wind loads.

f) Construction loads including erection forces and transportation loads.

2) [I] Basic loads on all structures except bridges shall be as defined in ASCE 7 except as clarifiedand supplemented below:


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a) Live loads include the following loads:

i) Personnel, portable machinery, tools, and equipment.

ii) Material to be temporarily stored during maintenance, such as exchanger parts, pipe andfittings, valves.

iii) Material normally stored during operation such as tools, maintenance equipment,

catalyst, and chemicals.

b) Fluid loads are the gravity loads resulting from liquid, solids such as packing, catalyst orinerts, or fluidized solid materials in equipment and piping during operation or hydrotest.

c) Piping restraint loads are forces on pipe anchors and guides resulting from thermal expansion,surge, or internal pressure of the piping.

d) Impact loads are loads that account for the dynamic effects from moving equipment such astraveling cranes, elevators, hoists, and vehicular traffic.

e) Bundle pull load is force resulting from the removal of a tube bundle from a heat exchanger.

f) Surge vibration loads are lateral inertia forces caused by the surging action of fluidized solids.

g) Construction loads are temporary loads caused by the erection and construction of structuresand equipment, such as loading from guy rigging, shoring, etc.

h) Transportation loads are inertial loads caused by the movement of structures and equipmentfrom a fabrication site to the installation site.

3) [I] Basic loads shall be determined according to the applicable codes and standards listed inSections 1 and2 as modified or supplemented herein.

3.2. Live Loads

1) [R] Minimum live loads which shall be used to design structural elements and appurtenances shallbe per ASCE 7 except where values in Table 1 are larger.

Table 1: Minimum Live Loads

Component Design Loaded Area Minimum Live Load (1)

Walkways and Access Platforms 5.0 kPa

Floor Plate, Grating and Slabs Platforms for Operating Storage orMaintenance Storage Loads.

6.0 kPa

Walkways and Access Platforms 3.0 kPa or a Moving Concentrated Loadof 4.5 kN

Floor Framing and BracingPlatforms for Operating Storage orMaintenance Storage Loads.

6.0 kPa

Walkways and Access Platforms 3.0 kPa or a Moving Concentrated Loadof 4.5 kN

Columns and BracketsPlatforms for Operating Storage orMaintenance Storage Loads.

6.0 kPa

Roof (Sloped or Flat) 1.0 kPa

Note (1): May be reduced based on influence area per ASCE 7

3.3. Wind Loads

1) [I] Wind loads shall be calculated based on procedures provided in ASCE 7 with the followingadditions/clarifications.


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a) Site specific wind design parameters as appropriate for the applicable code/standard shall beas specified by the Owners Engineer.

b) Exposure category C shall be used unless the terrain condition of the site justifies a differentterrain category subject to the approval of the Owners engineer.

c) Gust effect factors for flexible building and structures may be calculated by alternate methods

acceptable to the Owners Engineer. A building or structure shall be considered flexible onlyif it has a fundamental natural frequency less than 1Hz.

d) Force coefficients (Cf) for typical petrochemical facilities not specifically covered by ASCE7, such as multiple-bay open-frame structures containing equipment, pipe racks, vessel with

appurtenances, etc., shall be determined based on guidelines provided in ASCE Publication

40262: "Wind Loads and Anchor Bolt Design of Petrochemical Facilities."

e) The total wind force on equipment support structures may be determined as the sum of theforces on each component in the structure. Components shall include: equipment and

supports (without considering shielding), piping, structural framing, ladders, stairs, and other

miscellaneous objects attached to the structure. However, the total force due to wind for an

ordinary structure need not exceed that of an enclosed structure that would completely

envelope the structure and attachments.

3.4. Earthquake Loads

1) [I] Earthquake loads for building structures shall be calculated and applied in accordance withASCE 7 with the following additions/clarifications:

a) Site specific seismic design parameters as appropriate for the applicable code/standard shallbe as specified by the Owners Engineer.

b) Load factors applied to earthquake loads shall be consistent with the strength (limit states)design or allowable stress design method, as appropriate.

c) When a dynamic analysis is required by the applicable code, it shall be based on the seismic

response spectrum method to determine the earthquake forces and structural response.

2) Earthquake loads for tanks designed according to API STD 650 and API STD 620 shall be per theseismic provisions provided in the Appendices of those standards.

3) Earthquake loads for non-building structures shall be calculated and applied in accordance withASCE publication 40264: Guidelines for Seismic Evaluation and design of Petrochemical

Facilities with the following additions/clarifications:

a) Site specific seismic design parameters as appropriate for the applicable code/standard shallbe as specified by the Owners engineer (refer report titled Probabilistic Seismic Hazard

Analysis for the Papua New Guinea Gas Pipeline Project).

4) Earthquake loads for bridges shall be calculated and applied per PG-PDS 04-99-17.

3.5. Process Loads

1) [I] The operating contents of vessels including liquid, catalyst, inert balls, packing, etc. shall betreated as Fluid loads per ASCE 7 and shall be based on the maximum level that may occur

during operation.

2) [I] Vibration loads shall be based on process design or equipment specifications, or manufacturerdata, whichever is governing. They shall be considered as live loads in the selection of load

factors or safety factors in the applicable load combinations.

3) [I] Surge vibration loads for support structures and vessels for fluid-solids shall be per PG-PDS04-01-04. Load factors and combinations shall be subject to Owners engineer's approval.


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4) [R] Impact loads for hoist and equipment handling facilities shall be as follows:

a) Impact load shall be considered a variable load, similar to live load in the selection of loadfactors, safety factors, and load reduction factors in the applicable load combinations.

b) Vertical, lateral, and longitudinal impact loads on the supports for moving bridge cranes,trolleys and davits, and monorail cranes shall be per ASCE 7.

c) Davits (exclusive of manhole davits) shall be designed for the weight (mass) of the heaviestpiece of equipment that they may be required to lift, plus the weight of rigging equipment,

plus the impact load, but not less than a total load of 4.4 kN. Design shall be based on use of

a single sheave pulley block. All davits shall be legibly marked with the safe working load

(SWL).

d) Impact loads for other moving equipment shall be determined in conjunction with theequipment manufacturer.

5) [R] Thermal loads shall be considered for support structures, foundations, and elements thereofbased on the effects of differential temperature, and shall reflect the following:

a) Thermal loads shall be considered as a self-straining force per ASCE 7 in the selection of load

factors or safety factors in the applicable load combinations.b) Thermal effects shall be based on the difference between ambient or equipment design

temperature and the installed temperature, whichever is more severe.

6) [R] Forces due to sliding friction shall be considered as a self-straining force per ASCE 7 andshall be based on the following coefficients of static friction:

a) PTFE on PTFE: 0.10

b) Steel on Steel: 0.40

c) Steel on Concrete: 0.45

d) The coefficient of static friction for use on proprietary sliding surfaces and coatings shall beper the manufacturers specification and is subject to Owners engineers approval.

7) [R] Pipe anchor and guide loads produced from thermal movement, internal pressure, and surgeshall be considered as a self-straining force per ASCE 7 for determining applicable load

combinations and allowable stresses or load factors, as appropriate.

3.6. Maintenance Loads

1) [M] Bundle pull loads shall be considered for structures and foundations supporting heatexchangers subjected to bundle pulling during maintenance based on the following:

a) Bundle pull load shall be a longitudinal force equal to 100 percent of the tube bundle weight,but not less than 9.0 kN, applied at the centroid of the tube bundle.

b) Bundle pull load shall be considered as a live load.

c) Bundle pull force (shear) shall be assumed transmitted by only one (either) shell support,unless specified otherwise.

3.7. Construction Loads

1) [I] Construction loads shall be determined in conjunction with the erection contractor andequipment manufacturer.

2) [R] Transportation loads for structures and equipment shall be as follows:

a) Transportation loads for sea going transport shall be based on the most extreme conditionsfrom a minimum 10-year seasonal storm for the worst part of the route. Roll, pitch, and


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heave motion response of the barge/ship shall be developed in conjunction with the

transportation contractor.

b) Transportation loads shall be considered as a variable load per ASCE 7 for the selection ofload factors or safety factors in the applicable load combinations.

3.8. Other Loads1) [I] Vehicular loads shall be determined as follows:

a) For tired-vehicles (moving equipment) that operate on paved areasaccording to PG-PDS 04-99-17.

b) For railway equipment that operates on tracks-according to the applicable industry standards

2) [I] Hydrostatic Loads and Buoyancy shall be considered when a structure or equipment extendsbelow water level, either temporarily or long-term as follows:

a) Structure or equipment shall be considered as empty when evaluating impact of buoyancy.

b) Water table level shall be assumed to be at grade unless otherwise approved by the Owners

Engineer.c) Treatment of external hydrostatic pressure and buoyancy loads shall be the same as ground

water load per ASCE 7.

3.9. Load Combinations, Allowable Stresses, and Load Factors

1) [O] Loading conditions for buildings, structures, equipment, and foundations shall be according toASCE 7, plus the load combinations shown in Table 2.

Table 2: Applicable Loads for Loading Conditions

Operation

Loads Erection Testing Empty(Shutdown)

NormalAbnormal

(Upset)

Dead (Fixed) Loads

Dead Load of Structure X X X X X

plus fireproofing X X X X

Dead Load of Equipment X X X X X

plus internals, fireproofing, insulation X X X X

Dead Load of Piping plus insulationX X X X

Construction Loads

Forces caused by erection X

Live (Moveable) Loads

Platform and walkway loads X X X X

Material storage X X X X

Process Loads

Normal fluid loads X


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Operation

Loads Erection TestingEmpty

(Shutdown)Normal

Abnormal

(Upset)

Shutdown fluid loads X

Thermal forces X X

Vibrating equipment forces X X

Impact forces X X

Normal surge forces X(4)

Abnormal surge forces X(4)

Maintenance Loads

Test fluid loads X

Bundle pull force X (3)

Environmental Loads

Snow, ice or rain X X X X X

Earthquake (1) X X

Wind, 3 second gust (1) 80% of fullwind X (2) X X X (2)

Notes:

(1) Wind and Earthquake are not considered to act simultaneously.

(2) 1/3 full wind load or wind at 20 m/s, whichever is greater.

(3) Bundle Pull shall not be combined with Wind or Earthquake.

(4) Normal and abnormal surge loads shall be treated as variable loads. Load factors and combinations shall be subject toOwners engineer's approval.

2) [R], [C] Design should be based on the load combination causing the most unfavorable effect.When excluding loads other than dead loads results in a more critical loading condition, then such

exclusion shall be considered. Load factors and combinations are subject to Owners engineer's

approval.

3) [R], [C] For modifications or additions to existing structures, reduced load factors or higherallowable stresses may be used with the approval of the Owners engineer.


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Attachment: Purpose Codes Definitions

Code Description

C Assigned to paragraphs containing specifications whose primary purpose is reduced costs.

Reduced cost in this context refers to initial investment cost and does not include Life-Cycle

cost considerations. Life-Cycle cost considerations are captured under reliability,

maintainability, or operability purpose codes.

E Assigned to paragraphs containing specifications whose primary purpose is driven by

environmental considerations. Environmental considerations typically include specifications

intended to protect against emissions/leakage to the air, water, and/or soil. Deviations from the

specifications contained in such paragraphs require formal review and approval according to

local environmental policy.

I Assigned to paragraphs that provide only clarifying information such as Scope statements,definitions of terms, etc.

M Assigned to paragraphs containing specifications whose primary purpose is to provide for

maintainability of equipment or systems. Maintainability provisions are those that facilitate the

performance of maintenance on equipment/systems either during downtimes or during on-

stream operations.

O Assigned to paragraphs containing specifications whose primary purpose is to assure

operability of equipment or systems. Operability is the ability of the equipment/system to

perform satisfactorily even though conditions are off-design, such as during startups, process

swings, subcomponent malfunction, etc.

R Assigned to paragraphs containing specifications whose primary purpose is to improve or

assure the reliability of equipment or systems. Reliability is a measure of the ability of

equipment/systems to operate without malfunction or failure between planned maintenance

interventions.

S Assigned to paragraphs containing specifications whose primary purpose is avoidance of

personnel or operational safety incidents. Any deviation from the specifications contained in

such designated paragraphs requires formal review and approval according to local safety

policy.

Personnel Safety: Refers to the avoidance of recordable personnel injuries; i.e., burns, cuts,

abrasions, inhalation, or exposure to dangerous substances, etc., that

could result in medical treatment, restricted work, lost-time incidents, or

fatalities.Operational

Safety:

Refers to the prevention and control of process releases, fires, explosions,

etc.

pghu-eh-cspds-000103 rev 0 - design loads for structures

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