— A Practical Guide for Engineers, EPCs, and Project Teams
Refineries are among the most instrument-intensive industrial facilities. A single refinery may have thousands of measurement points—pressure, temperature, level, flow, and analytical—each feeding data to control systems that must operate with near-perfect reliability. Unlike many other process industries, refineries often run for years between turnarounds, requiring instrumentation that is not just accurate but robust, maintainable, and safety-certified.
This guide covers the key instrumentation requirements for refinery projects—from process unit selection criteria through to cable specification and installation practices.
1. The Refinery Challenge: What Makes It Different?
Refineries present a combination of challenges that distinguish them from other industrial facilities:
| Challenge | Impact on Instrumentation |
|---|---|
| Corrosive media | Sour crude (H₂S), naphthenic acid, chlorides attack instrument wetted parts |
| High temperatures | Furnace temperatures exceed 800°C; distillation column bottoms reach 350°C+ |
| High pressures | Hydrocracker reactors operate at 10–20 MPa |
| Flammable atmosphere | Extensive hazardous areas (Zone 1 and Zone 2) requiring Ex-certified instruments |
| Continuous operation | Refineries run for years between turnarounds; instruments must be reliable and maintainable online |
| Variable feedstocks | Crude oil composition varies; instruments must maintain accuracy across changing conditions |
The key principle: Refinery instrumentation must be selected for survival in corrosive, high-temperature, high-pressure environments—not just for measurement accuracy.
2. Applicable Standards and Design Basis
Refinery instrumentation design is governed by a combination of international and industry-specific standards. API RP 551 provides recommendations about the selection and design of process measurement systems, covering the instrumentation life cycle including selection, design, installation, commissioning and operation--.
2.1 Key API Standards
| Standard | Scope |
|---|---|
| API RP 551 | Process Measurement Instrumentation—selection and design of process measurement systems- |
| API RP 553 | Refinery Valves and Accessories for Control and Safety Instrumented Systems—selection, specification, and application of control valves- |
| API RP 554 | Process Control Systems—functions and functional specification development for oil and gas production, refinery, and petrochemical services- |
| API RP 555 | Process Analyzers—application of analyzers and associated systems, installation, and maintenance- |
| API RP 556 | Instrumentation, Control, and Protective Systems for Fired Heaters- |
| API 2350 | Overfill Protection for Storage Tanks in Petroleum Facilities- |
2.2 Key IEC and Other Standards
| Standard | Scope |
|---|---|
| IEC 61511 | Functional safety—Safety Instrumented Systems (SIS) for the process industry sector; applies to oil refining-- |
| IEC 60079 / GB 3836 | Explosive atmospheres—Ex certification for instruments in hazardous areas |
| BS 6739:2024 | Instrumentation in process control systems—installation design and practice; provides recommendations for good practice on site- |
| IEEE 1810 | Installation of circuit-integrity cables evaluated for hydrocarbon pool fires in petroleum and chemical facilities- |
2.3 Key Chinese Standards
| Standard | Scope |
|---|---|
| GB/T 50892 | Instrumentation and control system design for oil and gas fields and pipelines—covers instrument selection, installation, cabling, and earthing- |
| GB 50058 | Electrical installations in explosive hazardous areas |
| SY/T 6503 | Combustible and toxic gas detection and alarm systems |
3. Instrument Selection by Process Unit
3.1 Crude Distillation Unit (CDU) and Vacuum Distillation Unit (VDU)
The CDU is the refinery's first process unit, separating crude oil into fractions. The VDU distills heavy residue under vacuum.
Key measurements:
| Measurement | Recommended Technology | Critical Considerations |
|---|---|---|
| Column pressure | AP transmitter (vacuum service for VDU) | High accuracy at low pressures (millibar range) |
| Column temperature | Type K thermocouple (up to 350°C) | Thermowell insertion depth: 1/3–2/3 of column diameter |
| Bottom level | DP level transmitter with remote seal | High temperature (350°C+); remote seal protects transmitter |
| Reflux flow | Coriolis or vortex flowmeter | Flow measurement with temperature compensation |
| Overhead vapour pressure | GP transmitter | Low-pressure measurement |
CDU and VDU distillation units require comprehensive instrumentation and monitoring-. For vacuum service, absolute pressure (AP) transmitters are essential for measuring column top vacuum—standard gauge pressure transmitters cannot measure below atmospheric pressure.
3.2 Fluid Catalytic Cracking Unit (FCCU)
FCC converts heavy gas oil into lighter products. The reactor section requires pressure monitoring in the 0–25 MPa range-.
Key measurements:
| Measurement | Recommended Technology | Critical Considerations |
|---|---|---|
| Reactor pressure | GP transmitter with Hastelloy diaphragm | High temperature; catalyst abrasion; H₂S corrosion |
| Regenerator pressure | GP transmitter | Temperature extremes; catalyst dust |
| Reactor-regenerator DP | DP transmitter | Critical for catalyst circulation control |
| Reactor temperature | Type K or N thermocouple | High-temperature ceramic thermowell |
| Flue gas O₂ | Zirconia analyser | Combustion efficiency |
Pressure monitoring in catalytic cracking units at the reactor section requires transmitters with high accuracy (±0.075%) within the 0–25 MPa range-. For high-temperature oil and gas service, remote seal transmitters with高温合金 diaphragms protect the transmitter from heat while transmitting pressure through capillary tubing-.
Selection criteria:
Wetted materials: Hastelloy or Inconel for H₂S and high-temperature service
Ex certification: Ex d IIC T4–T6 or Ex ia IIC T4–T6
Remote seal with高温硅油 fill for reactor service
3.3 Hydrocracker / Hydrotreater
Hydrocracking operates at high pressure (10–20 MPa) and high temperature, with hydrogen and H₂S present.
Key measurements:
| Measurement | Recommended Technology | Critical Considerations |
|---|---|---|
| Reactor pressure | High-static-pressure GP transmitter | 32 MPa static pressure capability; Hastelloy wetted parts |
| Reactor temperature | Multipoint thermocouple | Temperature profiling across catalyst bed |
| Reactor level | Guided wave radar or DP with remote seal | High pressure; high temperature |
| Feed flow | Coriolis flowmeter | High accuracy for mass balance |
| Hydrogen flow | Thermal mass flowmeter | Low-pressure-drop measurement |
| Fractionator level | DP level transmitter | Distillation column service |
Multipoint temperature instruments with thermocouple sensors are widely used to monitor for optimum heat distribution and prevent hotspots and premature catalyst deactivation under high-temperature conditions-. Abrasion and H₂S contamination must be factored in when specifying design limits-.
SIL requirements: Hydrocracker safety functions often require SIL 2 or SIL 3 rated instruments. IEC 61511 sets out best safety practices for implementing safety instrumented systems in the process industry-. The SIS must be independent from the process control system (PCS) and comply with IEC 61511-.
3.4 Delayed Coker
Delayed coking converts heavy residue to petroleum coke and lighter products. Coke drums present one of the most challenging environments for level measurement-.
Key measurements:
| Measurement | Recommended Technology | Critical Considerations |
|---|---|---|
| Coke drum level | Radiometric (gamma) level measurement | Non-intrusive; unaffected by fouling, foam, or changing process conditions- |
| Coke drum temperature | Type K thermocouple | High temperature; thermal cycling |
| Coke drum pressure | GP transmitter | Pressure control during coking cycle |
| Fractionator level | DP level transmitter | Service with heavy hydrocarbons |
Monitoring the level of tower bottom liquids in a delayed coker is among the most important measurements in a refinery-. With neutron-based backscatter solutions no longer available, radiometry is now the only viable technology for reliable level measurement in delayed coking units-.
3.5 Catalytic Reformer
Catalytic reforming produces high-octane gasoline components and aromatics, operating at high temperature and pressure with hydrogen recycle.
Key measurements:
| Measurement | Recommended Technology | Critical Considerations |
|---|---|---|
| Reactor temperature | Multipoint thermocouple | Temperature profiling across catalyst bed |
| Furnace tube temperature | Skin thermocouple or pyrometer | Tube wall temperature monitoring |
| Reactor pressure | GP transmitter | Hydrogen service; Ex d IIC |
| Recycle gas flow | Orifice plate + DP transmitter | Hydrogen-rich gas; high pressure |
Multipoint temperature measurement for reforming reactors requires sensors that withstand high temperatures and hydrogen service.
3.6 Utility Systems
Refinery utility systems—steam, cooling water, instrument air, fuel gas—require instrumentation for reliable operation-.
| Utility | Key Measurements | Recommended Technology |
|---|---|---|
| Steam | Pressure, temperature, flow, drum level | GP/DP transmitters, RTDs, vortex flowmeters |
| Cooling water | Flow, temperature, pressure | Magnetic flowmeters, RTDs, GP transmitters |
| Instrument air | Pressure, dew point | GP transmitters, dew point analysers |
| Fuel gas | Pressure, flow, calorific value | GP transmitters, vortex flowmeters, gas chromatographs |
4. Instrumentation Cable Requirements
Instrumentation cables in refineries must withstand high temperatures, potential chemical exposure, and fire risk-.
4.1 Cable Types and Construction
| Cable Type | Construction | Application |
|---|---|---|
| Instrumentation cable | Twisted pair, shielded, 300/500V | 4-20mA signals, RTD, thermocouple- |
| Intrinsically safe cable | Low capacitance, blue sheath (IEC 60079-14) | IS circuits in hazardous areas |
| Fire-resistant cable | Mica tape + XLPE/EPR, IEC 60331 | ESD, fire pumps, critical SIS circuits |
| Armoured cable | STA or SWA, LSZH sheath | Direct burial, mechanical protection |
Instrumentation circuits for refinery plants measure pressure, flow and transmit low-voltage signals to instrument or control rooms-. Twisted pair cables are used for most process instrumentation (4-20mA, RS485)-.
Cable insulation materials commonly used in refineries include PVC, XLPE, and halogen-free plastic or silicone blends-.
4.2 Shielding Configurations
| Configuration | Best For |
|---|---|
| Overall Screen (OS) | General protection against external EMI |
| Individual Screen (IS) | Eliminating crosstalk between pairs in multi-pair cables |
| IS + OS (Dual Screen) | Critical analogue signals in high-EMI environments |
4.3 Fire Performance Requirements
Refineries require cables with specific fire performance:
| Requirement | Standard | Application |
|---|---|---|
| Flame retardant | IEC 60332-1 / -3 | General instrumentation cables |
| Fire resistant (circuit integrity) | IEC 60331 | ESD, fire pumps, SIS |
| Low smoke zero halogen (LSZH) | IEC 60754 / IEC 61034 | Control rooms, enclosed spaces |
| Hydrocarbon fire resistant | IEEE 1810 / NEK 606 HCF | Offshore and high-risk refinery areas- |
5. Installation Best Practices
5.1 Mounting Position
| Service | Recommended Position |
|---|---|
| Gas | Transmitter above tapping point; impulse lines slope downward to transmitter |
| Liquid | Transmitter below tapping point; impulse lines slope upward to process |
| Steam | Transmitter below tapping point with condensate pot |
5.2 Impulse Lines
Slope: ≥1:10 for proper drainage/venting-
Length: Keep as short as practical
For corrosive/crystallising media: Use isolation tanks, heat tracing, and insulation-
BS 6739:2024 provides recommendations for the design for the installation of instrumentation of measurement and control systems in the process industry-.
5.3 Cable Installation
| Practice | Why |
|---|---|
| IS and non-IS cables separately routed | Prevents energy transfer to IS circuits |
| Shielded cables with proper grounding | Prevents EMI and ground loops |
| Instrument trays at the bottom | In stacked tray arrangements, lowest voltage at the bottom |
| Separation from power cables: ≥300 mm | Prevents EMI-induced signal noise |
Cable routing should be designed using 3D modelling techniques integrated with分层敷设 principles, with完备屏蔽接地 measures-.
5.4 Grounding
Protection earth: ≤4Ω resistance-
Instrument earth: Isolated from safety earth
IS earth: Dedicated for intrinsically safe circuits
Shield grounding: Single-point grounding at control room end for analogue signals
6. Why Choose Anhui Tiankang for Refinery Instrumentation?
Anhui Tiankang (Group) Co., Ltd. has been manufacturing industrial instruments and cables for nearly five decades. Our refinery instrumentation solutions are trusted by major EPC contractors and refinery operators worldwide.
Complete refinery instrumentation portfolio:
| Category | Products | Refinery-Specific Features |
|---|---|---|
| Pressure | TK1151/3051 GP/AP/DP transmitters, remote seals | 316L/Hastelloy/Monel wetted parts, NACE MR0175 compliance, Ex d/Ex ia IIC |
| Temperature | Thermocouples (K, N, S, R, B), Pt100 RTDs, thermowells, multipoint sensors | High-purity elements, ceramic/Inconel thermowells, ASME PTC 19.3 TW design |
| Level | Radar level transmitters (TKLD series), guided wave radar, DP level transmitters | Non-contacting, Ex ia/Ex d, SIL-rated switches |
| Flow | Orifice plates, vortex flowmeters, electromagnetic flowmeters, Coriolis flowmeters | SIL 2/SIL 3 options, abrasion-resistant liners |
| Instrumentation cables | IS/OS/LSZH/fire-resistant cables | Low capacitance, Ex-ia certified, LSZH sheaths |
| Ex cable glands | Ex d/Ex e certified glands | ATEX/IECEx certified, brass/stainless steel |
Core advantages:
Complete certifications: CCC Ex, ATEX, IECEx, SIL2/SIL3, CCS marine
CNAS-accredited laboratory: Full performance testing for refinery applications
Material options: 316L SS, Hastelloy C-276, Monel, tantalum, titanium
Proven track record: Long-term supplier to CNPC, Sinopec, CNOOC, and international EPC projects
One-stop supply: From instrumentation to cables to Ex glands—one supplier, one interface
7. Conclusion
Refinery instrumentation requires a systematic approach that addresses the unique challenges of corrosive media, high temperatures, high pressures, and hazardous atmospheres.
Key takeaways:
| Aspect | Key Principle |
|---|---|
| Standards | API RP 551, IEC 61511, and BS 6739 provide the foundation |
| Pressure | Remote seals for high temperature; NACE compliance for H₂S service |
| Temperature | Type K/N thermocouples for high-temperature zones; multipoint for reactor profiling |
| Level | Radiometric for coke drums; radar or DP for storage and process tanks |
| Flow | Coriolis for custody transfer; vortex for steam and gases |
| Cables | IS/OS shielding, LSZH sheaths, fire resistance for critical circuits |
| Installation | Correct slope, separation, grounding per BS 6739 and GB/T 50892 |
Remember: Refineries run for years between turnarounds. The instruments you specify today will be in service for decades. Specify the right materials, the right certifications, and the right installation practices—because in refinery service, reliability is not optional.
Contact Us
For refinery instrumentation selection advice, technical documentation, or project quotations, please contact:
Yin Shuangjie
International Sales Manager
📧 Email: [email protected]
📱 WhatsApp / Zalo: +86 17856068126
🌐 Website: http://www.tiankang-global.com/
Anhui Tiankang – Your partner for reliable refinery instrumentation solutions.
