A Shutdown Postmortem - Reducing Cable Failures Caused By Sub-Standard Cable Jointing

By Chris Dodds on 6th March, 2015

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Hazardous Area Cable Joints

Power supplied by electric cables is the lifeblood of the oil and gas industry : uninterrupted power ensures oil and gas production, processing, transportation, storage and distribution.

However, cables are vulnerable to damage and degradation in harsh onshore and offshore operating conditions. 

Cable failure is catastrophic. Cable related problems are costly and are often caused by inadequate risk identification, sub-standard design or deficiencies in installation technique.

Whatever your currency, cable failures cost millions. The financial costs, both direct and consequential, can be painfully calculated. The reputational loss is immeasurable.

Unplanned shutdowns or suspended production caused by electrical power outages associated with cable failures can and does inflict devastating revenue losses on the oil and gas industry.

3M have a proven history in providing tested and trusted solutions for the jointing and terminating of cables in the oil and gas industry.  

 

3M & T&D3M

T&D are 3M's largest UK stockist for their range of 3M Scotchcast Cable Joints, Terminations & Abandonment Kits for installation in safe or hazardous area zones encountered in the oil and gas industry.

Consequently, T&D are regularly requested to provide specification guidance and technical support for the cable jointing of power, control and instrumentation cables in Zone 1 and Zone 2 hazardous areas.

In this article we shall focus on why, when and where 3M Scotchcast cable joints are the established solution for jointing low voltage power, control and instrumentation cables in the global oil and gas industry.

The usual questions posed by electrical engineers are :

"Do You Stock ATEX Cable Joints?"

or 

"Which Cable Joint Is Best Suited For Hazardous Areas?"

 

Let T&D Clarify & Advise....

According to Sira Ex Certification Manager, "cable joints do not come under ATEX 94/9/EC as they are classed as partATEX Hazardous Area of the cabling system." Sira is a world leader in the conformity assessment solutions field, specialising in explosion safety of equipment used in potentially explosive atmospheres (ATEX & IECEx).

Cables are not certified for use in hazardous areas but the requirements for suitable cables and cable joints are covered in EN IEC 60079-14, Installation In Hazardous Areas.

Effectively this implies the jointing of cables in hazardous areas are covered under good practice according to DSEAR (ATEX 137) regulations.

 

ATEX Demystified

3M cable joints and more generally cable accessories (cable terminations, cable joints, cable abandonments) are not within the scope of the ATEX 94/9/EC directive.

The ATEX Directive covers a broad range of Electrical Equipment for installation in hazardous areas encountered in market sectors such as offshore oil rigs, gas platforms, onshore oil refineries, petrochemical plants, underground coal mines, flourmills and other areas where a potentially explosive atmosphere may be present.

In broad terms, there are 3 pre-conditions for the ATEX Directive to apply :

  • Equipment must have its own source of ignition ;
  • Be intended for use in a potentially explosive atmosphere (air mixtures) ; and
  • Be under normal atmospheric conditions

When used as directed, 3M cable joints do not have a source of ignition - 3M Electrical Products provide ongoing cable jointer training to ensure installer familiarity with "best-practice" for hazardous area cable jointing.

The firing of an explosive atmosphere may be caused by a short circuit, but when cable joints are installed according to the joint kit instructions, 3M cable joints are safe against short circuits. 3M cable joints can be expected to demonstrate faultless service for the entire lifecycle of the cable installation.

 

Why Specify & Install 3M Resin Cable Joints In Hazardous Areas?

A Shutdown Postmortem.

Following shutdown disruptions the real challenge is to identify the cause to avoid history repeating itself via a technique often referred to as Root Cause Analysis (RCA).

Pin-pointing a cable failure to a specific set of causes can enable planning to prevent future recurring failures. RCA should drive up operational reliability and kill the original cause of the disaster.

The dangers of under-specified cable joints for oil and gas industry installations cannot be under-estimated. 

An oil company was experiencing problems with the earth continuity of a low voltage feeder. The problem was narrowed down to a heat shrink cable joint. On investigation it was obvious the heat shrink material had not reacted well to the years of hydrocarbon attack. The butyl mastic inner fill had turned to a sticky paste and the inner, connector insulation tubes had also suffered advanced degradation.

Pictured : Failed Cable Caused By Sub-standard Cable Joint Installation

Cable Joints

The cause of the earth continuity problem was due to poor connections onto the wire armours and subsequently liquid rubber isolating the armours from the earth continuity lead.

The cable joint had failed due to prolonged hydrocarbon attack. Hydrocarbons had penetrated the cable some distance away and travelled between the wire armours and inner sheath to the actual cable joint, and finally attacking the cable joint from within. 

Hydrocarbons attack the chemical backbone formulation of standard polyurethane resin joints causing gradual degradation of the resin and eventual premature failure of the electrical cable joint.

3M hazardous area cable joint kits provide long term hydrocarbon resistance in extreme hazardous areas including Zones 1 and Zone 2. 3M offshore cable joints are suitable for power and instrumentation topsides cables to IEC/NEK606 and halogen-free mud resistant cables (BFOU and RFOU) types.

Pic : 3M Scotchcast Resin Cable Joints LVI3 Series (Flame Retardant, Hydrocarbon Resistant, Halogen Free)  

Hazardous Area Cable Joints

In applications where cables may be subjected to attack from hydrocarbons including oils, solvents, gases or other chemicals, designers and installers of critical cabling systems have historically relied upon using conventional lead-sheathed cable to provide maximum protection.

3M hydrocarbon resistant cable joints are suitable for paper (PILC) and polymeric (EPR, XLPE) insulated cables, with steel wire armour (SWA) or galvanised/phosphur bronze wire braided cables, with or without lead covered cable sheaths.

Standard polyurethane resin cable joints are not designed to withstand the extreme service conditions endured in the oil and gas industry -  this could include exposure to hydrocarbons, pollution, weathering, corrosion and chemicals. 

Whether hydrocarbons are airborne in a hazardous area on an offshore platform or present in contaminated soils on an onshore petrochemical plant, there is a clear requirement for higher specification cable joints. Therefore, this includes underground cable joints or jointed cables fixed onto cable containment (such as cable tray or ladder) by cable cleats or ties.

 

Scotchcast 1402FR

3M Hazardous Area Cable Joints utilise 3M Scotchcast 1402FR resin - 3M's unique formulated cable jointing resin is hydrocarbon resistant and specifially designed to encapsulate cable joints for installation in the oil and gas industry. 

3M Scotchcast Resin (1402FR) Product FeaturesScotchcast 1402FR 

  • Flame Retardant
  • Halogen Free
  • Resistant To Chemicals
  • Excellent Adhesion To Metals And Plastics
  • Hydrophobic Behaviour During The Curing Process
  • Excellent Hydrolytic Stability
  • Available With Closed Mix And Pour Delivery System

 

Why Play With Fire?Hazardous Area Explosive Atmosphere Zone 1 Zone 2 

Although fire safety is paramount there are definetly no fire and rescue services on an offshore platform.

The lack of an immediate fire service presents significant concerns for Health & Safety in an environment exposed to inflammable gases and potentially explosive atmospheres.

Consequently, lead electrical engineers are challenged with designing-out risk through careful specification of cables and accessories that eliminate or minimise danger. All thought and effort is geared towards preventing sparks. 

Clearly, hot-working poses serious dangers with respect to ignition sources. Naked flames required for heat shrink cable joints can ignite gas vapours in potentially explosive atmospheres  - air, naked flames and the presence of atmospheric combustible substances trigger the Ignition Triangle. 

The employer is required to carry out a risk assessment under the requirements of framework directive (89/391/EEC). Directive 99/92/EC introduced specific legal requirements aimed at protecting workers from the dangers of potentially explosive atmospheres.

DSEAR ATEX 137 Hazardous Areas

 

Video Training : Jointing Power Cable In Hazardous Area Using 3M Scotchcast Cable Joints (LVI3 Series)

 

Conclusion

3M Scotchcast hydrocarbon resistant resin cable joints are a cold-pour, cold-install solution for first class safety and reliability without any hidden dangers.

When specifying, installing and purchasing cable joints the actual material cost should always be contexted with the potential real cost of a product failure, in terms of time, reputation and money. 

Should you require any further information or assistance with the specification of cable joints for power, control or instrumentation cables in safe or hazardous area zones in the oil and gas industry please do not hesitate to call us.

 

Selection Guides : 3M Scotchcast Resin Cable Joints (Power, Control & Instrumentation)

 

About 3M3M Cable Joints
3M captures the spark of new ideas and transforms them into thousands of ingenious products. Our culture of creative collaboration inspires a never-ending stream of powerful technologies that make life better. 3M is the innovation company that never stops inventing. With $30 billion in sales, 3M employs 88,000 people worldwide and has operations in more than 70 countries. For more information, visit www.3M.com

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Category:  LV Cable Jointing & Terminating

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