3103+-+Level+Transmitter

FORMAT No. Ref. PROCEDURE No. ISSUE No. REV. No. REV. DATE: ODS/SOF/004A / B ODS/SOP/008 TO 015 01 01 15/210/2003

Spec. No.: 3103

Rev. No.: 0

Discipline: Instrumentation

Page: 1 of 10

OFFSHORE DESIGN

SECTION

FUNCTIONAL SPECIFICATION FOR

LEVEL TRANSMITTER


LEVEL TRANSMITTER

PREPARED / REVISED BY

REVIEWED BY APPROVED BY

TOTAL No. OF PAGES

DATE REV. No.

ET MC AC 2 13.05.2003 0


Spec. No.: 3103

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LEVEL TRANSMITTER

CONTENTS

Clause No. ITEM Page No.

1.0 Scope Of This Document 3

Standards And Specifications 3

2.1 Reference Specifications 3

2.0

2.2 Other Specifications To Be Followed 3

3.0 Scope Of Supply 3

Level Transmitters 4

4.1 General 4

4.2 Displacement Type Level Transmitter 4

4.3 Differential Pressure Type Level Transmitter 5

4.4 Accuracy 5

4.5 Reading scales 5

4.0

4.6 Material 5

5.0 Equipment Protection 6

6.0 Installation Requirement 6

7.0 Calibration, Inspection And Testing 6

8.0 Documentation 7

9.0 Tagging & Nameplates 7

10.0 Review And Approval 7

11.0 Vendor Pre-Qualification Requirements 7 12.0 Preparation For Shipment 7

13.0 Receipt And Storage 7

Annexure I Material Selection Chart For Level Transmitters 8

Annexure II Hook Up Drawing for Level Transmitters 9


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LEVEL TRANSMITTER

1.0 SCOPE OF THIS DOCUMENT:

1.1 This specification describes the essential considerations in the selection, installation, calibration, testing and commissioning of Level Transmitters.

1.2 The Contractor shall be responsible for the selection of the Level Transmitters suitable for its intended application, its procurement, packing, calibration, testing at yard and offshore, shipment to yard and offshore site, installation and commissioning at site.

2.0 STANDARDS & SPECIFICATIONS:

2.1 Project Specifications: a) Specification No. 3.6: Instrumentation Design Criteria b) Project Basic Bid Work c) Project P & IDs

2.2 Other Specifications To Be Followed: NIL

3.0 SCOPE OF SUPPLY:

3.1 The number of Level Transmitters to be supplied and installed shall be as per the requirements indicated in the Basic Bid Work and the P & IDs.

3.2 The scope of supply shall also include commissioning spares and two years spares as required by clause 3.6.4.8 of Instrumentation Design Criteria, and as suggested by the Manufacturer.


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4.0 LEVEL TRANSMITTERS:

4.1 General:

4.1.1 A local / integral indicator shall be provided with each level transmitter.

4.1.2 The transmitter shall be intrinsically safe and shall be capable of operating on 24 V DC and providing 4-20 mA output signal. The load driving capability shall be 600 ohm at 24 V DC in 2-wire system.

4.1.3 Alternative level instruments such as capacitive, nucleonic, ultrasonic, etc., shall not be used without the Companys approval.

4.1.4 All level instruments shall be provided with piping isolation valves.

4.1.5 The drain valves from all level instruments shall be piped into the platform drain system.

4.2 Displacement Type Level Transmitter:

4.2.1 Displacement type level instruments shall be used for all process control applications where level variation in the vessel is not beyond 1219 mm (48"). Displacer length shall be selected to fully utilize the surge capacity of the vessel. External displacer cages, segregated from the vessel by two block valves, shall be used. External cage level instruments shall have pressure ratings equal to or greater than the relevant piping classification requirements for flanged block valves on the vessel.

4.2.2 External displacer cages shall be supplied with side/side connections. Where this is not possible top/bottom or side/bottom connections may be provided. Side / top connections shall be used only in cases where this would avoid a pocket in the connecting pipe. Connections for external cages shall be 2 ANSI flanged.

4.2.3 Internal displacer cages shall be used only with atmospheric vessels without side appurtenances. No isolation valves are needed for such applications. For internal type, connection shall be 4 ANSI flanged top mounted.

4.2.4 Rotatable heads shall be provided with displacer type instruments.

4.2.5 The torque tube material shall be Inconel. The cage to head connection shall be flanged.


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LEVEL TRANSMITTER

4.2.6 For external cages, block valves shall be installed in horizontal position of both lines at the vessels. If a vertical nozzle is used the valve shall be arranged so that no sediment pockets are present. A valve shall be installed to permit draining each displacer cage and piped to drip pans or deck drains.

4.2.7 A positive seal shall be used in transferring float / displacer motion to the external mechanism where a float or displacer element is employed.

4.3 Differential Pressure Type Level Transmitters:

4.3.1 Differential pressure type level transmitters may be used where the application requires wide throttling ranges and fluid Specific Gravity is constant.

4.3.2 Differential pressure type level measurement is acceptable for remote level indication. For level range of 1219 mm (48") and above, this type of transmitter shall be used for all services; seals shall be provided as required. These instruments shall have zero elevation/ suppression adjustment wherever required.

4.4 Accuracy:

4.4.1 The maximum error shall not exceed 1% of the span.

4.5 Reading Scales:

4.5.1 Units for level indicating scales shall be 0 100 percent.

4.6 Material:

4.6.1 The material requirements for level transmitters / instruments shall in general be according to clause 3.6.4.5 of Instrumentation Design Criteria and the material selection chart provided in Annexure I of this specification.

4.6.2 The cage material shall be compatible with the vessel material, and shall be Carbon Steel as a minimum. Flange material for external cages shall be Carbon Steel as a minimum.

4.6.3 All flanges on the level instrument pressure retaining parts shall be of the same type and rating as the process flanges and shall be in accordance with the vessel trim specification.

4.6.4 Torque tube when used shall be of Inconel / Monel minimum, with nylon bushing type bearings. All other wetted parts shall be SS 316 minimum, unless otherwise specified.


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LEVEL TRANSMITTER

5.0 EQUIPMENT PROTECTION:

5.1 Level Transmitter protection requirements shall in general be as per clause no. 3.6.4.4 of Instrumentation Design Criteria.

5.2 The level transmitter shall be weather proof to NEMA 4X / IP 66.

5.3 All level instruments in toxic and hydrocarbon service shall have blowdown connections to closed drain.

6.0 INSTALLATION REQUIREMENTS:

6.1 The installation of level transmitters shall in general be according to clause 3.6.4.6 of Instrumentation Design Criteria and as per Annexure II of this document.

6.2 External displacer type level instruments shall have block valves on both valves on both equalizing lines. These block valves shall be installed in the horizontal plane.

6.3 The equalizing lines and cages on external displacer type level instruments shall not be common with any other service. The minimum equalizing line size shall be DN 50.

6.4 Drain valves shall be provided to drain each displacer cage. This drain shall be piped or tubed to the platform closed drain system.

6.5 For dirty process services, displacer cage vents shall be connected to the utility water system to allow flushing of the cage.

6.6 The lower equalizing connection for a pipe column shall not come from the bottom of the vessel unless an internal stub-in with 90o elbow (looking downstream) is provided, or another method is used to prevent sediment collecting in the pipe column.

7.0 CALIBRATION, INSPECTION & TESTING:

7.1 Calibration, inspection and testing requirements shall in general be as per clause 3.6.4.7 of Instrumentation Design Criteria. In addition, the following shall also be taken care of:

7.2 Displacer type instruments shall be checked by raising and lowering mechanically the displacer and checking the pilot or transmitter action. Transmitters shall be checked with output gauges or meters for smooth and full output range. Shipping stops shall be reinstalled prior to shipping of module to the installation site.


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7.3 Differential pressure type level instruments shall be calibrated after installation against a manometer or precision pneumatic calibrator at three (3) points prior to installation. A precision output meter, gauge or manometer shall be used to monitor the output of transmitters.

8.0 DOCUMENTATION:

8.1 The documentation requirements shall in general be according to clause 3.6.6.2 of Instrumentation Design Criteria.

8.2 The vendor shall furnish intrinsic safety certificate from approved statutory body.

9.0 TAGGING & NAMEPLATES:

9.1 Tagging & Nameplate requirements shall in general be according to clause 3.6.6.1 of Instrumentation Design Criteria.

10.0 REVIEW & APPROVAL:

10.1 Review and approval of purchase specifications and other related documents shall in general be according to clause 3.6.6.3 of Instrumentation Design Criteria.

11.0 VENDOR PRE-QUALIFICATION REQUIREMENTS:

11.1 The Vendor pre-qualification requirements shall in general be according to clause 3.6.6.4 of Instrumentation Design Criteria.

12.0 PREPARATION FOR SHIPMENT:

12.1 The level transmitters shall be prepared for shipment in accordance to clause 3.6.6.5 of Instrumentation Design Criteria.

13.0 RECEIPT & STORAGE:

13.1 Receipt and storage of the level transmitters shall be in accordance to clause 3.6.6.6 of Instrumentation Design Criteria.


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ANNEXURE I

Material Selection Chart for Level Transmitters

Level Instrument S. No. Piping Class Body Displacer / Float

1

A1, B1, D1, E1, F1, XF1, F1, PA1, PB1, PD1, PE1, PXF1, PF1, A2, B2, D2, E2,

XG1, A1H, A3, B3, A8 (EXCEPT WAT. INJ. SERVICE)

CARBON STEEL SS 316

2

INJECTION WATER SERVICE

CARBON STEEL MONEL

3

A4, A6, A9, B9, D9, E9

SS 316 SS 316

4

A5

MONEL MONEL

5

A7

CARBON STEEL TEFLON LINED SOLID TEFLON

6

A1N, B1N, D1N, E1N, F1N, XF1N, PA1N, PB1N, PD1N, PF1N, XG1N

SS 316 SS 316

7

A10, B10, D10, E10, F10

SS 316 L SS 316 L

8

A11, B11, D11, E11, F11, PA11, PB11, PD11, PE11, PF11

MONEL 400 MONEL 400


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LEVEL TRANSMITTER

ANNEXURE II

HOOK UP DRAWING LEVEL TRANSMITTER

DETAIL 1

DETAIL 2 DETAIL 3


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OFFSHORE DESIGN

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LEVEL TRANSMITTER

ANNEXURE II (Contd.)

DETAIL 4

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3103+-+Level+Transmitter