Table of Contents
1. Scope
2. General
3. Instrumentation by Equipment Supplier
4. Instrumentation by Purchaser
5. Documentation
6. Specific Requirements
7. Selection of Instruments
Attachments
I Aplicable Standards and Regulations (Ref. BN-SP-K1 paragraph 11.1 and 11.2)
II Instrument Connections on Piping and Vessels (Ref. BN-SP-K1 paragraph 12.2.1 and 12.2.2)
III Ranges of Level Instruments (Ref. BN-SP-K1 paragraph 12.3.2 )
IV Installation of Thermowells (Ref. BN-SP-K1 paragraph 12.3.4)
Symbol explanation
o Feature required
o Feature not required
o Vendor to specify
1. Scope
This specification covers the general requirements and philosophy for instrumentation on equipment purchased as a “packge unit”.
Specific requirements are specified in the applicable equipment specification.
2. General
2.1 The equipment supplier will be responsible for the proper functioning of his equipment. Complete instrumentation required for unattended operation of the unit shall be shown on vendors documentation. The instrumentation provided shall be in agreement with local regulations and shall be adequate for the operating conditions as stated in the equipment requisition.
The scope of supply shall be as indicated on the engineering flow diagrams which are the governing documents.
2.2 To achive standardization with the process instrumentation the purchaser reserves the right to:
- Prescribe the use of particular makes and types of instruments
- Supply and install certain parts of the proposed instrumentation
- Prescribe the use of standardized process connections for instrumentation
- Suggest changes to the proposed instrumentation and control system.
All changes will be made in close cooperation with the equipment supplier which will remain responsible eor the proper operation of the equipment.
3. Instrumentation by Equipment Supplier
3.1 The vendor shall supply and install all instruments which from an integral part of yhe unit.In addition, the following items shall be provided.
- Special instruments not readily available, licensed or manufactured by vendor
- Gauge boards to group concentration of indicating instruments
- All initiating devices for alarm, safety interlocking and sequence control
- Pneumaticaly operated local loops
- Transmitters for main control room instrumentation.
3.2 When the requisition specifies factory assembled units, or when field installation is required the scope shall also include all required instrument cabling, and panels.
4. Instrumentation by Purchaser
4.1 Unless otherwise indicated, purchaser will provide folloving instrumentation in accordance with vendor’s requirements.
- Main control panel instrumentation
- Alarm systems
- Relay/logic systems.
5. Documentation
5.1 Vendors scope shall include, but not be limited to, following documentation.
- Engineering flow diagrams showing all equipment,piping and instruments required for proper control and operation of the unit for all cases specified
- Instrument process data sheet
- Instrument schedule
- Interlock and control diagrams
- Panel layout and wiring diagrams
- Instrument specification sheets
- Operating manuals.
5.2 The engineering flow diagram shall cleary show the control systems, the shut down and interlock systems, the location of instrumented safety devices, the fail action pf control valves, the limits of supply and the extent of any materials to be furnished by purchaser.
The diagrams will be reviewed by purchaser and returned with comments for vendor’s acceptance prior to other placement.
The symbols shall be in accordance with purchaser’s standards (Instrumentation as per ISA S-5.1).
At a later stage purchaser will designate instrument numbers.
5.3 Vendor shall notify purchaser in tender of make and type of instruments being proposed.
6. Specific Requirements
Following requirements shall be adhered to as much as possible, deviations shall be confirmed by vendor.
6.1 Instrument Connections
6.1.1 Instrument process connections shall be in accordance with Attachment II “instrument connections on piping and vessels”. All pressure connections shall have a block valve.
6.1.2 A standpipe must be used when more than one level gauge is required.
6.1.3 Level instruments shall have standard ranges as per Attachment III.
6.1.4 Thermowell installation shall be in conformity with Attachment IV.
6.1.5 Control valves 1 inch and above shall have flanged connections to ANSI B 16.5.
Face to face connections shall be in agreement with FCI-65-2
6.2 Instrument Signals and Supply
6.2.1 Local instrumentation shall be pneumatic and feature a standard signal of 0.2-1.0 barg.
Instruments should still work properly on a minimum air supply of 3.5 barg.
6.2.2 Transmission signal to/ from purchasers control room will be :
o pneumatic 0.2-1.0 barg.
o electronic 4-20 mA
6.2.3 The electricity supply for instruments will be as follows :
Control instrumentation
o 110 Volts AC 50 c/s
o ....
Relay/Logic systems
o 110 Volts DC with battery back-up
o ....
When this supply level is not feasible the alternative AC supply level for control instrumentation is available.
Voltage variations :
- AC+10%, -15%
- DC+20%, -15%
6.3 Instrument Installation
6.3.1 Instrument installation shall basically be in agreement with API-RP 550 amended to suit applicable regulations.
Electrical installation shall be based on the routing of cables on trays or in open conduit.
6.3.2 Pneumatic signal lines should be 6 mm OD copper tubing PVC covered, with brass compression fittings.
6.3.3 Instrument cabling shall terminate in junction boxes designed to accept purchasers external cabling.
6.4 Safety Relief System
6.4.1 Safety relief valves shall be provided for conditions as required by local regulations or API RP 520/521 whichever is governing.
6.5 Instrument Identification
Each instrument shall be suitably identified with a metal tag.Indicating instruments shall have a nameplate with service description.
7. Selection of Instruments
7.1 General
7.1.1 Materials of construction shall be consistent with, temperature, pressure and corrosion conditions.
7.1.2 All instrumentation located outdoors shall be of weatherproof construction, adequately protected against settled snow, ice and rain.
The minimum enclosure protection shall be IP55 unless otherwise specified.
Were instrument housing are necessary to meet these protection requirements these shall be supplied by the vendor and subject to approval by the engineer.
7.1.3 Instrumentation shall be suitable for use in the area defined in the equipment specification and/or data sheet.
A valid certificate of approval and other applicable documentation must be furnished by the vendor for each item of hazardous area instrumentation.
7.1.4 When referred to, applicable to package units with extensive instrumentation, instrumentation shall be selected as detailed in specification BN-SP-K1.
7.2 Flow Instruments
7.2.1 Flow measurement in general shall have sharp edged concentric orifice plates as primary devices.Orifices shall be calculated according to ISO-R 5167
Where this method is not satisfactory, other devices may be used such as integral orifice meters, pilot tubes, venture tubes, rotameters positive displacement meters, etc. Primary element calculation shall be made available.
7.2.2 Vane type flow switches may only be used if the element can be removed during normal plant operation (i.e. batch operation, parallel trains etc.).
7.2.3 Rotameters shall be metal tube for general service.
Enclosed glass type may be used for nonhazardous/toxic fluids and purge applications below 10 barg system pressure.
7.2.4 Positive displacement meters shall have a filter upstream to protect the meter.
7.3 Level Instruments
7.3.1 Displacer actuated instruments are preferred for general applications up to a range of 1524 mm, for higher ranges differential pressure measurement shall be considered.
Where impractical due to solidification, viscous service or severe level fluctuation other measurement principles may be used.
7.3.2 Ball float actuated switches may be used for alarm and shut down applications.
7.3.3 Level instruments shall preferably be mounted externally to the vessel with valved connections.
7.3.4 Level gauges shall be as sembled from no. 9 size glasses.
Where more than four glasses are necessary, multiple gauges shall be used.
7.4 Temperature Instruments
7.4.1 Liquid filled systems shall not be used for operating temperatures in excess of 250OC.
Mercury filled systems shall not be used.
7.4.2 Termocuple elements will be chromel-alumel (type k) for temperatures up to 1100OC.
Temperature EMF curves shall conform to ISA C 96-1964.
Termocouple elements shall be of the mineral insulated metal sheathed execution with insulated tip, unless otherwise indicated.
7.4.3 For local indication dial thermometers with bi-metallic actuators may be used.
7.4.4 All temperature sensing devices shall be installed in protecting sockets or thermowells, drilled from solid material.
7.5 Local Panel Units
7.5.1 Local panels, where specified, shall be designed consistent with the number, type and usage of package unit instrumentation. The design shall take into account protective requirements for waterproofing and hazardous areas.
7.5.2 Steel sheet used for panel fabrication shall be 3 mm minimum.
7.5.3 Panel design shall permit satisfactory access to all components, instruments, terminal boxes, etc. , for operational and maintenance procedures but nevertheless comply with area classification requirements.
7.5.4 Proces fluids, including seal and lube oil shall not be piped into local panel units containing electrical circuitry.
Panels shall be supplied complete with all equipment and accesories for system operation, and fully piped and wired for site installation and connections.
Connections shall be provided for all pneumatic and electrical supplies and signals with all signal conditioning or supplies as integral part of the panel.
7.6 Alarm and Shut Down Systems
7.6.1 Relay systems and electronic control logic will in general be located indoors (purchasers main control room).
Where required, the local panel shall provide for duplicated information on process variables and alarm status.
7.6.2 Unless specified otherwise, instrumentation shall be designed and selected for a failsafe condition i.e. loss of instrument air and power supply shall not impair the safety of the process.
Shut Down initiating contacts shall generally be closed when process conditions are normal.
7.6.3 Alarm systems shall be self-contained solid state annunicators with integral 24 V DC power supplies.
All alarm channels shall include a voltage free repeat contact wired to terminations for the engineer’s exclusive use.
Alarm systems shall be “fail safe” in operation and use contacts which are closed at normal process conditions.
7.6.4 Shut Down systems, in general, shall be independent of alarm systems.
The activation of shut down devices shall be alarmed via an interposing relay activited by the primary shut down element.providing simultaneous but separate alarm and shut down functions.
Consideration may be givin to the use of solid state or pneumatic shut down systems where proprietary well proven components and systems are utilized.
7.6.5 Shut Down systems shall provide for the following inputs, outputs and functions.
- Start-up and maintenance override switches
- Fused isolate switches for each individual system
- Voltage free output contacts
- Signal lights shall have test features and be powered froma separately fused supply circuit.