Beware Exploding Sockets

Beware Exploding Sockets

Hytorc® bolting heads have long been regarded as a safer alternative to hammering on a striking wrench to remove stubborn case bolts.  But even impact sockets can shatter under extreme Hytorc® pressures, sending shrapnel rocketing across the turbine deck.  These explosive failures can cause serious injury or even death.

These failures can be reduced, but not eliminated, by using the correct socket. Impact rated sockets must be used at a minimum.    Old or worn sockets are of particular concern. Ill-fitting sockets do not fit tight on bolt heads.  This changes the stress points from the corners to the flats of the sockets and causes them to fail.  Best practice is to inspect sockets regularly and color code or otherwise identify them for this use. Another check for reliability would be to have the sockets inspected for potential indications of stress using NDE methods.  Hytorc® makes their own sockets and this may give an extra level of confidence.  However, in their safety note, Hytorc® only prohibits the use of altered, heavily used, damaged or chrome sockets.

Any socket can fail, so take steps to mitigate the result.  If possible, shroud the socket with a piece of pipe cut slightly bigger than the diameter of the socket and same height. If the socket fails, the pipe will hold everything inside. TGM is currently investigating a fiber impregnated tape designed to contain the debris. We also recommend tying off the head to prevent it dropping or flying off after a failure.

Be aware of your hydraulic forces.  Sockets are prone to failure when torqued more than twice the specified amount for assembly. Backup wrenches may not be rated for the torque applied.  Limit torque to the capacity of the weakest tool in the application.  Hytorc® publishes charts on their website which convert pump pressure to torque applied for each of their tools.

Finally, protect your personnel.  No one is to be in contact with the head or backup wrenches after initial clamping pressure is applied and until pressure is released. Determine the potential debris path and keep personnel away from the area. You can also use a piece of plywood or metal as a shield.  Face shielding is recommended as PPE for all personnel near the danger zone.

Remember that Hytorc® equipment is dangerous and must only be operated by trained individuals.  Best practice is to have the same person operate both the tool head and the pump.  When this is not possible, the pump operator must be in sight of the tool operator.  Three way communication must be used between them.

Loss of Lube Oil (Emergency Lube Oil Systems)

The International Association of Engineering Insurers found that the highest frequency of steam turbine failures worldwide is due to loss of oil. To minimize the effects of loss of oil events, all turbines have a backup or emergency oil system; however, checks of these backup systems are too often neglected. Should the backup systems be inoperable during a loss of power incident, the turbine can coast down with insufficient lubrication, causing expensive component failures. These failures can range from a loss of bearing integrity (wiped bearings) to major seal and rotating component damage, and they result in large costs to the turbine owner, not only in the repair of damage done, but in the cost of lost generation time.

Weekly maintenance checks on emergency lube oil systems should include verifying the adequacy of any battery backup system and testing the pressure switches and controllers that activate backup pumps. These tests should be performed to ensure the backup systems are fully functional should a loss of power or lube oil event occur. These simple efforts of prevention are inexpensive compared to the expenditures related to a turbine coming down without sufficient lube oil.

Safety Tips

At TGM, our motto is Safety, Quality, Production . . . In That Order! We currently have:

Zero OSHA Recordable Accidents for 528th Consecutive days!

Safety is Turbine Generator Maintenance’s top priority. TGM puts safety above all other considerations and expects that devotion from every TGM employee. Please see our dedicated Safety section of our website for more information on TGM’s Safety Program.

COMMON SENSE AND ACCIDENT PREVENTION

The experts say at least 80% of industrial accidents are caused by unsafe acts on the part of employees–and not by unsafe conditions. Here are a few actions, paired with safety suggestions:

  • Being in a Hurry – Don’t let the concern for completing a job quickly overshadow safety.
  • Taking Chances – Daring behavior or blatant disregard for safe work practices can put the whole work team at risk.
  • Being Preoccupied – If your mind is troubled or distracted, you’re at risk for an accident.
  • Having A Negative Attitude – Being angry or in a bad mood can lead to severe accidents because anger nearly always rules over caution.
  • Failing To Look For Hidden Hazards – Always be alert for changes in the jobsite environment. Hidden hazards include spilled liquids, out-of-place objects, unmarked floor openings, etc.

Awareness of your environment, self-preservation, and concern for your fellow workers are all factors in good common sense. All workers can prevent themselves from getting hurt.