Inspection of Rubber Insulating Blankets, Gloves and Sleeves

 

  Rubber Insulating Blankets

both Type I Natural or Polyisoprene synthetic rubber and Type II SALCOR elastomeric compound blankets are subject to damage by petroleum base products such as inhibitors, hydraulic fluid and transformer oils. Prompt removal of the petroleum base products is important to reduce swelling and damage likely to the blanket. If swelling does occur, it may eventually go down, but mechanical strength, that is, the blanket's resistance to snag, puncture and tear may be greatly reduced and deterioration of it's electrical insulating capacity may result. Depending on the petroleum base product involved, the contact area could become spongy and discolored.

It is difficult to inspect blankets properly by looking at a flat surface. In order to locate defects such as swelling, scratches, tears, abrasions, snags, corona cutting or age-cracking, the blankets should be rolled two times on each side, with the second roll at a right angle to the first roll. Blankets that show any of the above defects should be removed free from service.

The ASTM In-Service Specification F479 calls for an electrical retest at an interval not to exceed one year. In addition to the electrical test, a visual inspection of blankets shall be made in the field by a designated maintained in satisfactory condition by the users. The frequency of this inspection shall be at intervals of not more than six months.

Blankets should always be stored flat or rolled in blanket roll-ups or canisters. They should never be folded, creased or compressed in any manner. Do not use tape of any type to hold the blankets in the rolled position. The adhesive plasticizer can damage the blanket surfaces if the tape is left on the blanket for several days or more.

 In use, Insulating Blankets must be held in place with one or more blanket fastening or holding devices. W. H. Salisbury & Co. offers a variety of fastening accessories such as blanket clamp pins, buttons, magnetic holders and Velcro TY Straps to give the user flexibility in selecting the fastening device best suited for each blanket application.

  

 

 

 Ozone damage caused by leaving Rubber Insulating Gloves in reversed position.

 

 

 Swelling caused by oil or grease left on a Rubber Insulating Glove. Chemical deterioration of the material soon follows.

 

 

 Rubber Insulating Gloves and Sleeves

Linemen's Rubber Insulating Gloves must be carefully inspected before each use. Rubber gloves shall be field air-tested before use each day and more frequently if there is cause to suspect any damage. They must be inspected inside and out. Gloves and Sleeves should always be stored with the bead on the outside- never inside out. Gloves should be stored in a glove bag, while sleeves should be stored in a bag or roll-up to protect against mechanical and chemical damage. The ASTM In-Service Specification F496 requires that the electrical retest interval not exceed 6 months for rubber gloves and 12 months for sleeves, in addition, a visual inspection of gloves and sleeves shall be made in the field by a designated person at intervals not to exceed 6 months.

If contact has been made with any petroleum base products, such as inhibitors, hydraulic fluids and transformer oils, the gloves and sleeves should be wiped clean with a rag as soon after the contact as possible. Failure to remove the petroleum based product promptly will result in the rubber swelling and ultimately deteriorating. The swelling will eventually disappear but it may result in a considerable reduction of mechanical strength and deteriorating of insulating capability at the point where swelling occurred.

When inspecting sleeves, the entire inner and outer surface of the sleeves should be examined to locate pinholes, cuts, scratches, abrasions, aging, corona cutting, oil markings or other mechanical injuries. Stretching or rolling the rubber between the fingers, or on a flat surface, will aid in revealing defects. If any of the above defects are found, the sleeves should be tagged and withdrawn from service. Rubber gloves are the basic protection from electric shock, because the hands are the most likely portion of the body to make contact with energized parts. In order for rubber gloves to provide protection, they should be put on before a person is in a position where it may be possible to reach or fall into energized lines or equipment. Many companies have a predetermined distance, while others require their workers to put on rubber gloves (and sleeves) at the base of the pole or structure prior to leaving the ground in an insulated aerial device. This policy assures that the gloves (and sleeves) will be worn when the work area is reached.

 

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Inspection of Rubber Insulating Protective Equipment

 

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