Inst Aids Calc CSM93020C1

OFFICIAL COPY - PDF Generated on 27-Feb-2008 CLIENT:

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CHARTERER:

PROJECT: Head Office

Engineering Office

5, Route de Fribourg PO Box 152 CH-1723 Marly Switzerland Tel. +41 26 439 99 20 Fax: +41 26 439 99 39 www.singlebuoy.com

Unit 2B-9-1, Level 9 Block 2B, Plaza Sentral Jalan Stesen Sentral 5 50470 Kuala Lumpur Malaysia Tel. (+603) 2773 5300 Fax: (+603) 2773 5399

SU TU VANG FIELD DEVELOPMENT SO17560

CLIENT NUMBER:

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TP017-SBM-ST-RE-112

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Rev.

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DOCUMENT DESCRIPTION:

VESSEL INSTALLATION AIDS: SNATCH BLOCK PADEYE CALCULATION

Status/ Revision

(dd-MMM-YYYY)

No. of Pages

Written by

Checked by

Group Leader Dept. Head

EPM Approval for Issue

C1

27-Feb-08

18

JAMIL

M. AKMAL

M. AKMAL

H. BOTTA

Date

INFORMATION ON STATUS: P I C V A X EPM

Preliminary for Information Internal Discipline Checking For Comments and Approval Valid for Construction Approved For Construction “As Built” Engineering Project Manager or Assigned Substitute

 Copyright Single Buoy Moorings Inc 2008

Ex No. : SB 81638

OFFICIAL COPY - PDF Generated on 27-Feb-2008

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VESSEL INSTALLATION AIDS: SNATCH BLOCK PADEYE CALCULATION SO17560

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REVISION STATUS / SUMMARY OF CHANGES

REVISION C1

REVISED CHAPTERS

REVISION DESCRIPTION For comments and approval

REASON FOR REVISION First issue

2


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TABLE OF CONTENTS 1.

GENERAL................................................................................................................................ 4 1.1 INTRODUCTION........................................................................................................ 4 1.2 SCOPE....................................................................................................................... 5 1.3 LAYOUTS .................................................................................................................. 5 1.4 REFERENCE DOCUMENTS..................................................................................... 6 1.5 REFERENCE DRAWING........................................................................................... 6 1.6 MATERIALS CHARACTERISTICS ............................................................................ 6 1.7 ACCEPTABILITY CRITERIA ..................................................................................... 7 1.7.1 Allowable Stress........................................................................................... 7 1.8 DESIGN LOAD........................................................................................................... 7

2.

LIFTING LUG DESIGN............................................................................................................ 7

3.

OVERALL STRUCTURAL INTEGRITY ................................................................................ 10 3.1 FINITE ELEMENT ANALYSIS ................................................................................. 10 3.2 BOUNDARY CONDITION........................................................................................ 11 3.3 LOADING ................................................................................................................. 11

4.

RESULTS SUMMARY........................................................................................................... 12

APPENDIX 1)

SHACKLE CATALOGUE ........................................................................................ 14

APPENDIX 2)

SMIT DOCUMENTS ................................................................................................ 15


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VESSEL INSTALLATION AIDS: SNATCH BLOCK PADEYE CALCULATION SO17560 1.

GENERAL

1.1

INTRODUCTION

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The Su Tu Vang field is located in Block 15-1 offshore SE Vietnam in relatively shallow water of about 51 m depth. The field is part of the Su Tu complex which includes two other areas namely Su Tu Den Southwest and Su Tu Den Northeast. Production from the Su Tu Den Southwest area commenced in October 2003 and remains at full production. The Su Tu Den Southwest production facilities include a wellhead platform (WHP-A) with primary separation facilities, tied back, via 4” pipelines to a Suezmax size FPSO. Facilities on the Su Tu Den FPSO include oil separation and treating, produced water handling, seawater injection and gas lift. The proposed Su Tu Vang development is a Central Production Complex comprising one unit each of the following: • • • •

A Floating Storage and Offloading (Su Tu Vang FSO) system A Central Processing Platform (CPP) Subsea pipeline end manifold (PLEM) Intra-field flowlines

Stabilised crude product from the CPP will be transferred to storage on the Su Tu Den FPSO. However, in the short term, the combined production from the existing Su Tu Den and the new Su Tu Vang will be in excess of the FPSO design capability. Therefore, additional storage capacity, the Su Tu Vang FSO, is required for this period. Crude oil is transferred to the Su Tu Vang FSO from the Central Processing Platform (CPP) by a pipeline and a flexible riser. The riser and pipeline are interconnected by a Pipe Line End Manifold (PLEM). Pipeline, flexible riser and rigid piping within the turret will form the fluid transfer system for this purpose. The turret is to be designed for at least 20 years with appropriate safety factors. The planned development has a target first oil date of October 2008.


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VESSEL INSTALLATION AIDS: SNATCH BLOCK PADEYE CALCULATION SO17560 1.2

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SCOPE The purpose of this document is to show the adequacy of the padeye and the surrounding structure to hold the pulling load from the snatch block during the installation. All primary structural elements are checked for compliance with the requirement of the international standards and regulations as mentioned in Ref. [4].

1.3

LAYOUTS

Figure 1.0: Plan View of Snatch Block Layout from Ref. [3].

Figure 2.0: Elevation View of Snatch Block Layout from Ref. [3].


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REFERENCE DOCUMENTS [1] SO17560

SSM 92010

SBM Standard steel plates and profiles specification.

[2] AISC – Allowable Stress Design – Ninth Edition [3] 07.429-002 Smit Engineering Memo: Dimensions, Positioning and Design Loads FSO Deck Equipment [4] American Bureau of Shipping Guide for building and classing: Floating production, storage and offloading system (May 2004)

1.5

1.6

REFERENCE DRAWING [i] SO17560

DSM 02017

Vessel Insert Padeye for Snatch Block

[ii] SO17560

DSM 02001

Tanker Insert General Arrangement

[iii] SO17560

DSM 82031

Rigid Arm General Arrangement

MATERIALS CHARACTERISTICS The lifting lugs are made from high strength steel (Grade 36) in accordance with Ref.[1] and the summary of the yield stress reduction with respect to the plate thickness is shown in table below. Properties Material Designation

High strength steel Grade 36

Thickness (mm) t ≤ 16 16 < t ≤ 40 40 < t ≤ 63 63 < t ≤ 80 80 < t ≤ 100

E (GPa)

ν

210

0.3

Table 1: Requirement for minimum yield strength

σ yield (MPa) 355 345 335 325 315


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ACCEPTABILITY CRITERIA

1.7.1

Allowable Stress

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The following table shows the maximum allowable combined comparative stresses according to Ref. [4] chapter 5 sections 4.13. Safety Condition

Condition

Operating

Minimum Yield Strength fy (N/mm2)

Allowable Stress (N/mm2)

355 345 335 325 315

213 207 201 195 189

0.6

Table 2: Allowable yield stress

1.8

DESIGN LOAD The design load of 100 tons acting on the snatch block is based on Ref. [3]. It is assumed that the design load given has included all the necessary factors and that maximum line tension between the snatch block and the gantry sheave is 170 tons..

2.

LIFTING LUG DESIGN Refer to Ref. Dwg. [i] for the lifting lug details. Allowable stress is in accordance to Ref. [4]. Design load =

100t (1,000 kN)

Assumed shackle size used Pin diameter Bow width Bow clear height

= 3 ½” Bolt Type Anchor Shackle (See Appendix 1) = 3.76” (96mm) = 5.25” (133mm) = 14.63” (372mm)

Check Shear on Padeye Shear area τ

= 2[(200-50)(30) + 2(200-75)(25)] = 21,500 mm2

= 1,000 E3 / 21,500 = 46.5 N/mm2

Allowable shear stress

= 0.4 Fy = 0.4 (345) = 138 N/mm2


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Check Bearing Bearing area

= =

96(25+30+25) 7,680 mm2

σbearing

= =

1 E6 / 7,680 130.2 N/mm2

Allowable bearing stress = 0.9 Fy = 0.9 (345) = 310.5 N/mm2 Check Welding on Cheek Plate Weld leg length

= 15mm

Throat length

= 15/√2 =10.6mm

Weld length

= 2π(175)(2) =2,200mm

Weld area

= 10.6 x 2,200 = 23,320mm2

Note: Assumed 50% of weld area is effective. τ = 1,000 E3 / (23,320 / 2) = 85.8 N/mm2 Allowable shear stress

= 0.4 Fy = 0.4 (345) = 138 N/mm2

Check Padeye Base Inline Moment

= 1000 kN x 0.5m = 500 kN.m

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= 5% x 1000kN x 0.92m = 46 kN.m

25

25

30 600

500 900

Inline Section Modulus

= 7.96 E6 mm3

Off plane Section modulus

= 3.01 E6 mm3

Shear area

= 900 x 30 = 27,000 mm2

σin line

= 500 E6 / 7.96 E6 = 62.81 N/mm2

σoff plane

= 46 E6 / 3.01 E6 = 15.3 N/mm2

τ = 1,000 E3 / 27,000 = 37.1 N/mm2

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VESSEL INSTALLATION AIDS: SNATCH BLOCK PADEYE CALCULATION SO17560 σcombined

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= (62.81 + 15.3) + 3(37.1) = 101.14 N/mm2 2

Allowable combined stress

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2

= 0.6 Fy = 0.6 (345) = 207 N/mm2

OVERALL STRUCTURAL INTEGRITY Considered loading is as per Section 1.8.

3.1

FINITE ELEMENT ANALYSIS The structure is modelled using the finite element method (NX Nastran version 4.1 as solver and FEMAP version 9.3 as pre and post processor). The original model used on has been modified to reflect the current design arrangement. Longitudinal extend of the model is from bulkhead frame 122 to rigid arm at 5850 forward of frame 122. Transverse extend is from longitudinal bulkhead at 4800 at starboard side to 4800 at port side. Vertical extend is from 31225 above base line to 34655 above base line. The model has been carried out and presented in the following image

Figure 3.0: 3 - Dimensional view of the model.


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VESSEL INSTALLATION AIDS: SNATCH BLOCK PADEYE CALCULATION SO17560 3.2

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BOUNDARY CONDITION The turret structure is model as pinned at deck at elevation 31225, rigid arm frame at 5850 forward of frame 122, bulkhead at 4800 of centreline at starboard and bulkhead at 4800 of centreline at port side.

3.3

LOADING Considered loading is as per Section 2. 1000 kN load is distributed onto 5 nodes. The distribution values are assumed to be as follows.

Figure 4.0: Load Distribution. Pont load at “a”

=

50 × 1000 [50 + 2(43.3) + 2(25)]

=268 kN Pont load at “b”

=

43.3 × 1000 [50 + 2(43.3) + 2(25)]

=232 kN

Pont load at “c”

=

25 × 1000 [50 + 2(43.3) + 2(25)]

=134 kN


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Figure 5.0: Load Application.

4.

RESULTS SUMMARY

Figure 6.0: Von-Mises Stress On Padeye

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Figure 7.0: Von-Mises Stress Existing Structure

Von Mises Stress Result Maximum Von Mises Stress, σ eq = 159.3 MPa < 0.6 (345) = 207 MPa Unity Check, UC = 0.77

OK

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VESSEL INSTALLATION AIDS: SNATCH BLOCK PADEYE CALCULATION SO17560 APPENDIX 2)

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Inst Aids Calc CSM93020C1

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