SWA Instrumentation Cable for Oil, Gas and Petrochemical Projects

An SWA instrumentation cable combines low-level signal transmission with Steel Wire Armour to provide additional mechanical protection in demanding industrial routes. This combination is particularly relevant to oil, gas and petrochemical projects, where instrumentation cables can run through refineries, process units, tank farms, compressor stations, utility areas and other locations exposed to impact, crushing, rodents or heavy construction activity.

However, SWA should not be specified simply because a project is located in the oil and gas industry. Armour primarily addresses mechanical risk. Signal shielding, conductor grouping, capacitance, insulation, fire behaviour, chemical resistance and hazardous-area requirements remain separate engineering decisions.

Therefore, the correct cable should match both the instrumentation circuit and the physical installation environment. A protected control-room route may need screening but no armour, while an exposed outdoor tray can justify a screened, XLPE-insulated, steel-wire-armored construction.

Quick answer: Use SWA instrumentation cable where the route creates a credible risk of mechanical damage and the project permits metallic armour. Select the pair or triad configuration according to the instrument circuit, choose overall or individual PiMF/TiMF screening according to EMI and circuit-isolation requirements, and then specify PVC or LSZH materials according to the environmental and fire strategy. SWA does not replace the instrumentation screen and does not by itself make a cable suitable for hazardous areas, direct burial or fire-resistant applications.

SWA Instrumentation Cable at a Glance

Project Requirement	Construction to Consider	Main Reason
Mechanical exposure	SWA instrumentation cable	Additional resistance to impact, crushing and external stress
Two-wire instrumentation circuit	Pair / TP construction	Matches typical two-conductor loop architecture
Three-wire instrumentation circuit	Triad / TT construction	Keeps three related conductors together
Moderate EMI	Overall-screened construction	Protects complete cable core against external interference
Sensitive multicircuit signals	PiMF / TiMF + overall screen	Adds circuit-to-circuit isolation
General industrial environment	PVC sheath where permitted	Practical industrial protection
Low-smoke / halogen-free requirement	LSZH / halogen-free construction	Supports project fire and smoke strategy
Outdoor route	UV-resistant outer sheath	Protects against long-term sunlight exposure
Hazardous area	Project-specified cable + approved installation system	Cable selection must follow the complete hazardous-area design

The important principle is that SWA solves only one part of the specification.

Consequently, an engineer should not use the term “SWA instrumentation cable” as a substitute for defining the complete electrical, mechanical and environmental construction.

What Is an SWA Instrumentation Cable?

An SWA instrumentation cable is a signal or control cable that includes a layer of galvanized steel wires around the inner cable construction.

The instrumentation core can carry analogue or digital measurement and control signals between field devices and systems such as:

• DCS
• PLC
• SCADA
• Marshalling cabinets
• Remote I/O
• Safety systems
• Monitoring equipment

Meanwhile, the Steel Wire Armour provides additional mechanical reinforcement around that signal cable.

Depending on the product family, the complete construction can therefore include:

• Copper conductors
• PE, XLPE or PVC insulation
• Pairs, triads or layered cores
• Individual PiMF or TiMF screens
• Overall Al/PET screen
• Tinned-copper drain wire
• Inner sheath
• Galvanized steel wire armour
• PVC, PE or halogen-free outer sheath

Why Is SWA Used in Oil and Gas Instrumentation?

Oil and gas facilities can expose cable routes to significantly more mechanical risk than a conventional commercial building.

For example, instrumentation cables may pass through:

• Open cable trays
• Process units
• Pipe racks
• Tank farms
• Compressor stations
• Pump areas
• Loading terminals
• Utility plants
• Outdoor junction-box routes
• Underground infrastructure

Heavy construction activity can also continue during plant expansion or maintenance.

As a result, cables can face:

• Impact
• Crushing
• Abrasion
• Rodent attack
• Installation damage
• External mechanical loading

Steel wire armour provides an additional protective layer against these hazards.

SWA Does Not Replace Instrumentation Shielding

This distinction is critical.

SWA primarily provides mechanical protection.

The instrumentation screen primarily addresses electromagnetic interference and signal integrity.

Although a metallic armour layer can interact with electromagnetic fields, it should not be treated as a substitute for the cable’s dedicated foil or braid screening system.

Therefore, a typical screened SWA instrumentation cable may include both:

• Al/PET foil screen + drain wire
• Galvanized steel wire armour

Each layer has a different engineering purpose.

Typical SWA Instrumentation Cable Construction

A common industrial SWA instrumentation cable can follow this sequence:

Layer	Typical Material	Function
1. Conductor	Stranded copper	Carries instrumentation signal
2. Insulation	XLPE, PE or PVC	Electrical insulation
3. Pair / triad assembly	Twisted insulated conductors	Groups conductors by circuit
4. Individual screen where required	Al/PET foil + drain wire	Pair-to-pair or triad-to-triad isolation
5. Overall screen	Al/PET foil + drain wire	External EMI protection
6. Inner sheath	PVC or halogen-free compound	Provides bedding beneath armour
7. Armour	Galvanized steel wires	Mechanical reinforcement
8. Outer sheath	PVC, LSZH or project-specific compound	Environmental and external protection

However, the exact construction varies between product families.

For this reason, engineers should work from the actual datasheet rather than interpreting the cable code alone.

Why Is an Inner Sheath Used Beneath SWA?

The inner sheath provides a stable bedding layer for the steel wires.

Without suitable bedding, the armour would sit directly against more delicate cable components such as screens or assembled signal elements.

Therefore, the inner sheath can help:

• Maintain cable geometry
• Separate armour from screens
• Provide a smooth armour bedding
• Improve mechanical stability
• Protect the underlying cable core

After the armour is applied, the outer jacket then protects the complete cable from the installation environment.

What Does the SWA Layer Protect Against?

Steel Wire Armour can provide useful protection against several mechanical hazards.

Impact

Industrial sites can expose cable to tools, equipment, construction materials and accidental physical contact.

Therefore, SWA provides an additional mechanical barrier before an impact reaches the signal core.

Crushing

Cables can encounter compression in heavy cable trays, underground sections or industrial infrastructure.

Consequently, the steel-wire layer can improve resistance to external mechanical loading.

Rodents

Steel armour creates a strong physical barrier against rodent penetration.

However, actual suitability should still follow the complete cable construction and route risk.

Installation Damage

Long industrial cable pulls can expose a cable to abrasion and mechanical handling.

In addition, construction sites can remain active around the installed routes.

As a result, SWA can provide useful additional protection throughout both installation and service life.

When Is SWA Instrumentation Cable Unnecessary?

More armour does not automatically create a better instrumentation system.

For example, a cable inside:

• Protected control rooms
• Enclosed cabinets
• Dedicated indoor trays
• Protected conduits
• Low-risk technical spaces

may face very little mechanical exposure.

In that situation, an unarmored screened instrumentation cable can provide:

• Smaller outside diameter
• Lower weight
• Greater flexibility
• Easier termination
• Lower material cost

Therefore, SWA should solve a real mechanical requirement rather than serve as a default oil-and-gas specification.

SWA vs Unarmored Instrumentation Cable

Characteristic	Unarmored	SWA
Mechanical protection	Basic cable construction	Additional steel-wire protection
Weight	Lower	Higher
Outside diameter	Smaller	Larger
Flexibility	Generally higher	Generally lower
Installation effort	Lower	Higher
Exposed industrial routes	May require additional pathway protection	Often more suitable
Protected control-room routes	Often sufficient	May be unnecessary

Therefore, the installation route should determine whether armour adds genuine engineering value.

SWA vs SWB for Instrumentation Cables

ETK also manufactures instrumentation cables using Steel Wire Braid.

SWA and SWB both provide additional mechanical protection, but their structures differ.

SWA uses galvanized wires arranged as an armour layer. By contrast, SWB uses interwoven steel wires.

As a result, SWB can provide greater flexibility in some constructions, while SWA remains attractive for demanding fixed routes requiring robust mechanical protection.

However, neither should be selected only from the acronym.

Engineers should compare:

• Mechanical risk
• Bending radius
• Cable diameter
• Installation route
• Tensile requirements
• Project specification

Pair vs Triad SWA Instrumentation Cable

The armour does not determine whether the cable should use pairs or triads.

Instead, the instrument circuit makes that decision.

A pair contains two related conductors and commonly suits:

• Two-wire 4–20 mA loops
• Analogue transmitter circuits
• Two-conductor signal circuits

Meanwhile, a triad contains three conductors and can suit:

• Three-wire RTDs
• Three-wire transmitters
• Other three-conductor measurement circuits

Therefore, the correct sequence is:

Choose pair or triad from the circuit → choose screening → evaluate SWA from the mechanical route.

Overall-Screened SWA Instrumentation Cable

An overall-screened construction places a common metallic screen around the assembled signal core.

For example, a typical design can use:

• Tinned-copper drain wire
• Al/PET foil
• Inner sheath
• SWA
• Outer sheath

This architecture provides external electromagnetic protection while keeping the internal cable structure relatively straightforward.

Therefore, it can be suitable where individual circuits do not require separate screens.

PiMF and TiMF SWA Instrumentation Cable

More demanding systems can use individual screens around each pair or triad.

PiMF provides an individual foil screen around each pair.

Meanwhile, TiMF provides an individual foil screen around each triad.

Afterward, manufacturers can assemble the screened elements and apply another overall screen before the inner sheath and SWA.

Consequently, the construction can provide:

• Pair-to-pair or triad-to-triad isolation
• External EMI screening
• Mechanical SWA protection

These are three distinct functions within one cable.

Overall Screen vs PiMF/TiMF for Refineries

Requirement	Overall Screen	PiMF / TiMF + Overall Screen
External EMI protection	Yes	Yes
Individual circuit isolation	Limited	Higher
Cable diameter	Generally smaller	Generally larger
Termination complexity	Lower	Higher
Material content	Lower	Higher
High-density sensitive circuits	Project-dependent	Often attractive

Therefore, individually screened construction should be justified by signal requirements rather than automatically added to every SWA cable.

XLPE Insulation in SWA Instrumentation Cable

XLPE is widely used in demanding instrumentation constructions because it provides strong electrical characteristics together with useful thermal and mechanical performance.

Compared with conventional thermoplastic insulation, XLPE can provide advantages involving:

• Temperature capability
• Insulation resistance
• Mechanical stability
• Electrical performance

For this reason, ETK uses XLPE in several RE-2X SWA instrumentation families.

However, XLPE alone does not define the cable’s screening, armour or fire performance.

PVC-Insulated SWA Instrumentation Cable

PVC insulation remains available in instrumentation constructions where the project and electrical requirements permit it.

For example, RE-Y(St)YSWAY combines PVC insulation, an overall Al/PET screen, PVC inner sheath, galvanized steel wire armour and a UV-resistant PVC outer sheath.

Therefore, PVC-based constructions can remain practical for conventional industrial applications where halogen-free performance is not required.

PVC vs LSZH Outer Sheath

The sheath system should follow the actual fire and environmental strategy.

PVC

PVC can provide:

• Good general mechanical durability
• Practical industrial performance
• Abrasion resistance
• Cost efficiency

However, conventional PVC produces smoke and halogen-containing combustion products during fire.

LSZH / Halogen-Free

Halogen-free sheath systems can reduce smoke density and corrosive halogen-related gases compared with conventional halogenated materials.

Therefore, they can be particularly relevant in:

• Enclosed process buildings
• Tunnels
• Control buildings
• Offshore structures
• Evacuation-sensitive locations

Nevertheless, LSZH does not automatically mean fire resistant.

RE-2X(St)YSWAY vs RE-2X(St)HSWAH

These two constructions illustrate how SWA can remain constant while the sheath system changes.

Characteristic	RE-2X(St)YSWAY	RE-2X(St)HSWAH
Insulation	XLPE	XLPE
Screening	Overall screen	Overall screen
Inner sheath	PVC	Halogen-free
Armour	Galvanized SWA	Galvanized SWA
Outer sheath	PVC	Halogen-free
Main selection distinction	Conventional industrial construction	Halogen-free fire/smoke strategy

Therefore, the armour designation alone does not define the fire-material behaviour of the cable.

RE-Y(St)YSWAY vs RE-2X(St)YSWAY

The difference between these families begins with the insulation system.

RE-Y… constructions use PVC-based insulation.

RE-2X… constructions use XLPE insulation.

Both can incorporate:

• Instrumentation screening
• PVC inner sheath
• SWA
• Outdoor PVC outer sheath

Consequently, engineers should not select between them simply because both contain SWA.

The electrical, thermal and project requirements should determine the insulation system.

ETK SWA Instrumentation Cable Families

Construction	Key Feature	Typical Selection Logic
RE-Y(St)YSWAY	PVC insulation + overall screen + SWA + PVC sheath	Conventional armored instrumentation route
RE-2X(St)YSWAY	XLPE insulation + overall screen + SWA + PVC sheath	Higher-performance XLPE construction
RE-2X(St)YSWAY PiMF/TiMF	Individual screens + overall screen + SWA	Greater circuit isolation in mechanically demanding routes
RE-2X(St)HSWAH	XLPE + overall screen + SWA + halogen-free sheath	Mechanical protection with halogen-free materials
RE-2X(St)HSWAH PiMF/TiMF	Individual screens + overall screen + SWA + halogen-free sheath	High circuit isolation + mechanical protection + halogen-free construction

This table shows why “SWA instrumentation cable” is only the starting point.

Screening, insulation and sheath architecture still need to be selected separately.

SWA Instrumentation Cable for 4–20 mA Loops

Two-wire 4–20 mA circuits commonly use twisted pairs.

If the cable route is mechanically exposed, the project can combine the pair-based instrumentation design with SWA.

For example, the cable can connect:

• Pressure transmitters
• Flow transmitters
• Level transmitters
• Temperature transmitters
• Control-system I/O

However, the mechanical need for armour remains separate from the electrical loop architecture.

SWA Instrumentation Cable for RTD Circuits

Three-wire RTD circuits can use triad-based instrumentation cable.

Where the route requires additional mechanical protection, that triad construction can also include SWA.

Meanwhile, individually screened TiMF designs can provide additional circuit isolation if the project requires it.

Therefore, a typical design sequence can become:

3-wire RTD → triad → TiMF if needed → overall screen if specified → SWA if mechanically required.

SWA Cable for DCS and PLC Systems

DCS and PLC installations often aggregate many field circuits into junction boxes and marshalling systems.

Therefore, multicircuit instrumentation cables can significantly reduce the number of individual cables required across a large plant.

Depending on the signal mix, the project can use:

• Multipair cable
• Multitriad cable
• Overall-screened cable
• PiMF/TiMF cable
• SWA versions of each construction

As a result, one cable family can serve many different field architectures while maintaining the required mechanical protection.

SWA Instrumentation Cable in Refineries

Refineries combine sensitive instrumentation with heavy industrial infrastructure.

Cable routes can pass near:

• Compressors
• Pumps
• Motors
• Variable-frequency drives
• Power distribution
• Pipe racks
• Process vessels

Therefore, the cable specification may need to address both EMI and mechanical risk.

An overall or individually screened instrumentation core can protect signal integrity, while SWA can provide additional mechanical protection around the complete cable.

SWA Instrumentation Cable in Petrochemical Plants

Petrochemical plants can contain long cable routes between field instruments and centralized control systems.

In addition, plant expansions and equipment modifications can increase the probability of accidental cable damage over the facility life.

For this reason, SWA can be useful on exposed fixed routes.

However, the project should also define:

• Chemical exposure
• Oil resistance
• UV resistance
• Temperature range
• Fire performance
• Screening
• Intrinsic-safety parameters

Armour alone does not address these requirements.

SWA Instrumentation Cable for Tank Farms

Tank farms can create long outdoor instrumentation routes between tanks, field devices and control infrastructure.

Consequently, cables may experience:

• UV exposure
• Temperature variation
• Rodent risk
• Mechanical maintenance activity
• Outdoor moisture

Therefore, a suitable outdoor sheath becomes as important as the SWA layer.

The complete product should be selected for the actual environmental conditions rather than relying only on the presence of steel armour.

SWA Instrumentation Cable for Compressor and Pump Stations

Compressor and pump stations contain rotating machinery and power equipment that can create both mechanical and electromagnetic challenges.

For this reason, instrumentation routes may require:

• Overall or individual screening
• Appropriate routing separation
• SWA mechanical protection
• Oil-resistant materials where specified
• Outdoor UV resistance

However, increasing armour does not improve the intrinsic EMI rejection of the instrumentation pair or triad.

Dedicated screening and installation practice remain essential.

SWA Instrumentation Cable for Offshore Platforms

Offshore installations can impose particularly demanding requirements on cable systems.

Projects may require combinations of:

• Mechanical armour
• Low-smoke materials
• Halogen-free construction
• Oil resistance
• Fire performance
• Marine or offshore approvals
• UV resistance

Therefore, a generic land-based SWA instrumentation cable should not automatically be assumed suitable offshore.

The actual platform specification and approval requirements should determine the complete product.

SWA Instrumentation Cable and Hazardous Areas

Oil, gas and petrochemical facilities contain hazardous-area zones where flammable gases or vapours may be present.

However, SWA itself does not make a cable “explosion proof.”

This distinction is important.

The hazardous-area installation normally depends on the complete system, including:

• Equipment protection concept
• Cable glands
• Sealing arrangements
• Grounding and bonding
• Intrinsic-safety design where applicable
• Local regulations
• Project specifications

Therefore, cable selection should follow the approved hazardous-area engineering philosophy.

SWA Instrumentation Cable in Intrinsically Safe Circuits

Intrinsic safety limits the electrical energy that can enter a hazardous area.

The cable can contribute capacitance and inductance to the complete loop.

Consequently, engineers may need to review:

• Mutual capacitance
• Conductor-to-screen capacitance
• Inductance
• Conductor resistance
• Loop length
• Barrier parameters
• Field-device parameters

SWA primarily provides mechanical protection and does not establish intrinsic-safety compliance.

Does SWA Affect Signal Integrity?

The primary signal-integrity features remain conductor geometry and dedicated screening.

For example:

• Twisting helps control induced noise
• Individual screens help isolate circuits
• Overall screens help reduce external interference
• Correct grounding helps the screen operate as intended

Meanwhile, SWA protects the complete construction against mechanical damage that could eventually affect cable performance.

Therefore, SWA protects signal reliability indirectly through physical protection rather than replacing the signal-screening system.

SWA Armour Grounding and Bonding

SWA introduces a conductive metallic layer along the cable route.

Consequently, the project may need to define bonding and grounding arrangements for the armour.

Important considerations can include:

• Building entry
• Hazardous-area gland systems
• Potential differences between locations
• Earth continuity
• Plant grounding philosophy
• Local electrical regulations

However, instrumentation-screen grounding and SWA grounding should not automatically be treated as the same connection.

The signal-screen termination philosophy can differ from the mechanical-armour bonding arrangement.

SWA and Instrumentation Screen Grounding Are Different

This point deserves particular attention.

An instrumentation foil screen exists primarily to control electrical interference.

SWA exists primarily for mechanical protection and forms a large conductive metallic layer.

Therefore, the engineering design may treat:

• Individual pair/triad drain wires
• Overall-screen drain wire
• SWA

as different conductive systems with different termination requirements.

Installers should follow the approved project grounding drawings rather than combining them arbitrarily.

Can SWA Instrumentation Cable Be Installed Outdoors?

Yes, when the complete product has an appropriate outdoor sheath.

However, steel armour alone does not establish outdoor suitability.

The outer jacket should provide the required:

• UV resistance
• Moisture resistance
• Temperature performance
• Chemical resistance where applicable

For this reason, ETK’s relevant outdoor SWA instrumentation constructions use UV-resistant outer sheaths.

Can SWA Instrumentation Cable Be Directly Buried?

Some SWA instrumentation cables may be designed for underground or direct-burial use, but this should not be assumed from the armour acronym alone.

A direct-burial specification can also require:

• Water protection
• Appropriate outer sheath
• Crush resistance
• Rodent protection
• Chemical resistance
• Suitable mechanical test values

Therefore, the actual datasheet and project specification should confirm burial suitability.

Can SWA Instrumentation Cable Run in Cable Trays?

Yes, fixed cable trays are a common industrial application.

SWA can be particularly useful where the tray is exposed to maintenance activity, impact or other mechanical hazards.

However, engineers should still consider:

• Tray loading
• Cable weight
• Bending radius
• Gland size
• Cable spacing
• EMC separation from power cables

Consequently, armour does not eliminate the need for good cable-route design.

Why Bending Radius Matters with SWA

Steel armour increases cable stiffness.

Therefore, an SWA cable normally requires more installation space than a comparable unarmored cable.

Problem areas can include:

• Junction-box entries
• Cable trays
• Vertical risers
• Control-room transitions
• Gland plates

For example, ETK publishes a 7.5 × D bending radius for RE-2X(St)HSWAH.

Consequently, designers should review actual product dimensions before finalizing tray and gland layouts.

Conductor Size in SWA Instrumentation Cable

Steel armour does not determine conductor cross-section.

The conductor size should follow the electrical loop requirement.

Common ETK instrumentation options include:

• 0.50 mm²
• 0.75 mm²
• 1.00 mm²
• 1.50 mm²
• 2.50 mm²

For example, ETK currently publishes these sizes across relevant RE-2X SWA constructions.

Selection should consider:

• Loop resistance
• Route length
• Voltage drop
• Signal type
• Device current
• Project requirements

SWA Instrumentation Cable Temperature Range

Temperature capability depends on insulation and sheath materials.

Therefore, engineers should not infer operating temperature from the SWA layer.

For example, ETK specifies a −30°C to +90°C operating range for its RE-2X(St)HSWAH construction.

However, other products can use different material systems and therefore different ratings.

The actual datasheet should always govern selection.

Fire Performance in SWA Instrumentation Cable

SWA does not make a cable flame retardant or fire resistant.

Those characteristics come from the insulation, sheath system and tested cable design.

Depending on the product, projects can require:

• IEC 60332 flame-propagation performance
• IEC 61034 smoke-density performance
• IEC 60754 halogen and corrosive-gas performance
• Other project-specific fire requirements

For example, ETK’s halogen-free RE-2X(St)HSWAH family lists IEC 61034-2, IEC 60754-1/-2 and IEC 60332 testing alongside its SWA construction.

Flame Retardant vs Fire Resistant SWA Instrumentation Cable

These terms should not be confused.

Flame retardant relates primarily to limiting flame propagation.

Fire resistant relates to maintaining a required circuit function during fire for a defined test period.

Therefore, an SWA instrumentation cable that passes a flame-propagation test should not automatically be described as fire resistant.

If circuit integrity is required, the project must specify the appropriate fire-resistant cable design and test standard separately.

Chemical and Oil Resistance

Refineries and petrochemical facilities can expose cables to hydrocarbons, lubricants and process chemicals.

However, a generic SWA construction does not automatically resist every substance.

For this reason, the RFQ should identify:

• Expected chemical
• Exposure duration
• Operating temperature
• Required test standard
• Required outer-sheath compound

The manufacturer can then confirm whether the proposed cable provides the necessary compatibility.

SWA Instrumentation Cable Standards

BS EN 50288-7 remains an important reference for multi-element metallic instrumentation and control cables used for analogue and digital signal transmission.

The standard covers mechanically robust instrumentation/control cable constructions and allows screening, optional armouring and environmental or moisture-protection layers.

Importantly, the standard framework does not mean every cable uses the same insulation, screen, armour or sheath.

Therefore, a complete project specification should still define:

• Conductor size
• Pair or triad arrangement
• Screening
• SWA requirement
• Insulation
• Sheath
• Fire behaviour
• Environmental performance

A Note on BS 5308 / PAS 5308 References

Older oil, gas and petrochemical specifications frequently reference BS 5308-style instrumentation constructions.

However, BSI withdrew PAS 5308-1:2009 and PAS 5308-2:2009 in April 2024. The current BS EN 50288-7 remains the relevant European instrumentation/control cable specification.

Therefore, purchasing teams should check whether an older project specification needs updating rather than copying legacy references automatically.

How to Select an SWA Instrumentation Cable

Question	If Yes	Selection Consideration
Does the route face mechanical damage?	Yes	Consider SWA
Does the circuit use two conductors?	Yes	Pair / TP construction
Does the circuit use three conductors?	Yes	Triad / TT construction
Is individual circuit isolation required?	Yes	PiMF / TiMF
Is only external EMI protection required?	Yes	Overall screen may be sufficient
Is LSZH required?	Yes	Halogen-free SWA construction
Is the route outdoors?	Yes	UV-resistant outer sheath
Is the route hazardous?	Yes	Follow approved hazardous-area design and cable-gland requirements
Is direct burial required?	Yes	Confirm full burial construction, not SWA alone
Is oil/chemical exposure expected?	Yes	Specify required compound resistance

Common Mistakes When Specifying SWA Instrumentation Cable

1. Assuming Every Oil and Gas Cable Needs SWA

Protected routes may not require additional steel armour.

2. Using SWA as an EMI Screen

SWA primarily provides mechanical protection. Dedicated instrumentation screens should address signal interference.

3. Assuming SWA Makes the Cable Explosion Proof

Hazardous-area compliance depends on the complete installation system and protection concept.

4. Ignoring Pair vs Triad Requirements

The field-device circuit should determine conductor grouping before armour is considered.

5. Specifying PiMF/TiMF for Every Circuit

Individual screening can increase diameter, weight and termination complexity when it is unnecessary.

6. Assuming SWA Means LSZH

SWA describes armour. PVC and halogen-free sheath systems are separate choices.

7. Assuming SWA Means Fire Resistant

Fire resistance requires a specific cable design and circuit-integrity test.

8. Assuming SWA Automatically Means Outdoor

Outdoor suitability also depends on the outer sheath and environmental specification.

9. Assuming SWA Automatically Means Direct Burial

Burial suitability requires confirmation of the complete cable design.

10. Ignoring Cable Weight and Bending Radius

Steel armour can materially increase handling and pathway requirements.

11. Ignoring Armour Grounding

Metallic SWA can introduce bonding and grounding requirements.

12. Connecting Instrument Screens and Armour Arbitrarily

The signal-screen and armour grounding philosophies can be different.

13. Choosing Insulation Only from the Cable Code

Electrical and temperature requirements should determine PVC, PE or XLPE selection.

14. Assuming LSZH Is Suitable for Every Outdoor Environment

Fire performance and outdoor environmental resistance are separate material requirements.

15. Ignoring Chemical Exposure

Oil and gas routes can require specific compound compatibility beyond generic industrial performance.

16. Reusing Legacy Standards Without Checking Status

Older project specifications may reference withdrawn standards and should be reviewed against current requirements.

What Should Be Included in an SWA Instrumentation Cable RFQ?

A request that states only “SWA instrumentation cable for refinery” leaves most of the engineering specification unresolved.

A useful RFQ should define:

• Number of cores, pairs or triads
• Pair / triad requirement
• Conductor cross-section
• Conductor class
• Conductor material
• Insulation material
• XLPE, PE or PVC requirement
• Overall screen requirement
• PiMF / TiMF requirement where applicable
• Drain-wire construction
• Maximum conductor resistance
• Maximum capacitance
• Inductance where relevant
• Operating voltage
• Intrinsic-safety electrical parameters where required
• Inner sheath material
• SWA requirement
• Armour material and construction
• Outer sheath material
• PVC or LSZH requirement
• UV resistance
• Oil resistance
• Chemical resistance
• Operating temperature
• Installation temperature
• Minimum bending radius
• Outdoor or indoor use
• Direct-burial requirement where applicable
• Hazardous-area installation requirements
• Flame-retardancy requirement
• Smoke-density requirement
• Halogen-free requirement
• Fire-resistance requirement if applicable
• Applicable EN, IEC or customer standard
• Cable marking
• Drum length
• Certificates
• Routine and type-test documentation

As a result, the manufacturer can quote a construction that solves the actual project requirement rather than simply adding SWA to a generic instrumentation cable.

ETK Kablo SWA Instrumentation Cable Solutions

ETK Kablo manufactures SWA instrumentation cable constructions for oil, gas, petrochemical, power, mining, tunnel, industrial and infrastructure projects.

The portfolio includes overall-screened and individually screened designs with different insulation and sheath systems.

RE-Y(St)YSWAY provides a PVC-insulated, overall-screened and steel-wire-armored construction for conventional industrial applications.

Meanwhile, RE-2X(St)YSWAY uses XLPE insulation together with overall screening, PVC inner and outer jackets and galvanized steel wire armour.

For applications requiring greater circuit-to-circuit isolation, RE-2X(St)YSWAY-PiMF/TiMF adds individual pair or triad screens before the overall screen and SWA.

Where the project requires halogen-free materials, RE-2X(St)HSWAH combines XLPE insulation, overall screening, halogen-free inner and outer jackets and galvanized steel wire armour. ETK also manufactures PiMF/TiMF variants of this construction for projects requiring both individual signal-element shielding and SWA mechanical protection.

Therefore, the appropriate ETK solution should be selected by separating four questions: circuit architecture, electromagnetic environment, mechanical exposure and environmental/fire requirements.

Frequently Asked Questions

What is an SWA instrumentation cable?

An SWA instrumentation cable is a low-level signal or control cable that includes Steel Wire Armour around the cable core to provide additional mechanical protection.

What does SWA mean?

SWA means Steel Wire Armour. Galvanized steel wires form a protective mechanical layer around the cable.

Why is SWA used in oil and gas projects?

SWA can protect instrumentation cables against impact, crushing, rodents and other mechanical risks common in exposed industrial routes.

Does every oil and gas instrumentation cable need SWA?

No. Armour should follow the mechanical conditions of the route. Protected indoor or conduit installations may not require it.

Does SWA provide EMI protection?

The cable’s dedicated foil or braid screen should provide the primary instrumentation EMI protection. SWA primarily addresses mechanical damage.

Can SWA instrumentation cable use PiMF?

Yes. Individually screened pairs can be combined with an overall screen and Steel Wire Armour.

Can SWA instrumentation cable use TiMF?

Yes. Individually screened triads can also be combined with an overall screen and SWA.

What is the difference between PiMF/TiMF and SWA?

PiMF and TiMF describe individual signal-element screening. SWA describes the mechanical steel-wire protection around the complete cable.

Can SWA instrumentation cable be LSZH?

Yes. SWA can be combined with halogen-free inner and outer sheath systems, such as ETK’s RE-2X(St)HSWAH constructions.

Is SWA instrumentation cable fire resistant?

Not automatically. SWA provides mechanical protection. Fire resistance requires a cable specifically designed and tested for circuit integrity during fire.

Is SWA instrumentation cable flame retardant?

It can be when the complete cable materials and construction meet the required flame-propagation tests. Armour alone does not provide that classification.

Can SWA instrumentation cable be installed outdoors?

Yes, when the complete cable includes an appropriate UV- and weather-resistant outer sheath.

Can SWA instrumentation cable be directly buried?

Some constructions can be suitable, but direct-burial suitability should be confirmed from the actual product and project specification rather than assumed from SWA alone.

Does SWA need grounding?

Steel armour can introduce bonding or grounding requirements. The arrangement should follow the plant’s electrical and hazardous-area grounding philosophy.

Should the instrumentation screen and SWA be grounded together?

Not automatically. Signal-screen termination and armour bonding can serve different purposes and should follow the approved project grounding design.

What is the difference between RE-2X(St)YSWAY and RE-2X(St)HSWAH?

Both can use XLPE insulation, overall screening and SWA. RE-2X(St)YSWAY uses PVC sheath materials, while RE-2X(St)HSWAH uses halogen-free inner and outer sheath systems.

What is the difference between RE-Y(St)YSWAY and RE-2X(St)YSWAY?

RE-Y(St)YSWAY uses PVC insulation, while RE-2X(St)YSWAY uses XLPE insulation. Both can use overall screening, PVC sheath systems and Steel Wire Armour.

Which SWA instrumentation cable is best for a refinery?

There is no universal best construction. The correct cable depends on circuit type, EMI environment, mechanical exposure, fire strategy, outdoor conditions, chemical exposure and project standards.

Is SWA cable suitable for 4–20 mA loops?

Yes. A screened pair-based SWA instrumentation construction can carry 4–20 mA loops when the cable’s electrical parameters meet the circuit requirements.

Can SWA cable be used for 3-wire RTDs?

Yes. A triad-based SWA instrumentation cable can support three-wire RTD circuits where its conductor and electrical characteristics meet the measurement-system requirements.

Which standard covers instrumentation cables?

BS EN 50288-7 is an important current reference for multi-element instrumentation and control cables used for analogue and digital signal transmission and allows screened, armored and environmentally protected constructions.

Conclusion

An SWA instrumentation cable provides a practical way to combine precision signal transmission with additional mechanical protection in oil, gas and petrochemical projects.

However, Steel Wire Armour should never become the starting point for the entire cable specification.

First, the field circuit determines whether the cable needs pairs, triads or another conductor arrangement. Next, the electromagnetic environment determines whether an overall screen or PiMF/TiMF individual screening is appropriate.

Afterward, the installation route determines whether Steel Wire Armour provides useful mechanical protection against impact, crushing, rodents or other physical risks.

Meanwhile, insulation and sheath systems address separate requirements. XLPE can provide strong electrical and thermal performance, while PVC and halogen-free sheath options serve different environmental and fire strategies.

Hazardous-area, intrinsic-safety, oil-resistance and direct-burial requirements also need independent engineering review. SWA alone does not make a cable explosion proof, intrinsically safe, fire resistant or suitable for every underground environment.

For engineers and purchasing teams, the most reliable approach is therefore to define the signal circuit first, screening architecture second, mechanical exposure third, and finally the insulation, sheath, environmental and fire-performance requirements needed by the actual oil, gas or petrochemical installation.