Basic types of adverse weather conditions (extreme temperature, freezing and wind) and the precautions to be taken.
1 Extreme Temperatures
Extreme temperatures affect the safety of personnel through loss of concentration.
1.1 Heat Stress:
This can be alleviated by protection from the heat source, and a plentiful supply of drinking water.
1.2 Cold Stress:
This can be fought against by:
- keeping clothing dry, clean and in loose layers,
- avoiding overheating and sweating,
- adequate meals,
- liquid intake (preferably warm).
On entering heated spaces, moisture and snow should be brushed off clothing. Openings in clothing should be adjusted to avoid overheating and sweating.
2 Icing and Freezing Conditions
2.1 General
When working in the Northern Seas, icing and freezing conditions, possibly connected with the occurrence of polar lows, can be expected during the winter season. Precautions are necessary to prevent systems from freezing and these include heat tracing, insulation, circulation, anti-freeze additives, steam heating and drainage.
2.2 Deicing
In addition to the above precautions if ice does form then several methods for deicing are available:
- Steam. The use of steam for de-icing should be carefully evaluated in case too low a temperature causes the steam condensate to freeze and quickly form solid ice. All steam hoses shall be drained properly after use and stored in heated areas.
- Compressed air. The use of compressed air is a clean method of removing ice but it may be necessary to mechanically break the ice before applying the compressed air. Alternatively compressed air may be used with steam de-icing to remove the water and condensate after defrosting with steam. All air hoses should be stored in heated areas after use.
- Seawater. Flushing with seawater is in most circumstances the best method although it is less efficient than steam. Its advantages are that seawater has a lower freezing point than steam condensate, does not freeze as fast, and also the ice crystals are smaller. The effect of wind causing additional water spray over the surrounding area should be considered.
- Vibration. Ice may be removed by mechanical vibration by hammering with pneumatic percussion tools etc. on all types of structure including the derrick and crane booms. If large amounts of ice are formed on the derrick, (eg: during logging runs, then between runs) the travelling block may be used if necessary to cause shocks or vibrations through the derrick to remove the ice; having first cleared the area of personnel.
2.3 Precautions
Further precautions may be necessary for particular systems or areas likely to be affected by icing or freezing, and are as follows:
2.3.1 Emergency Exits and External Escape Routes
All emergency exits leading to the open and external escape routes shall be continuously accessible and have non-slip surfaces during any weather conditions. If necessary emergency exits and escape routes should be de-iced.
2.3.2 Fire and Washdown Systems
The fire and washdown systems shall be continuously operable and all exposed parts shall be protected by heat tracing, insulation, water circulation or drainage as applicable.
2.3.3. Seawater Systems
All exposed parts of seawater systems shall be heat traced and insulated.
2.3.4. High Pressure Mud and Cement Systems
The mud system standpipe and kelly hose shall contain anti-freeze treatment liquid, or be properly drained when not in use.
The choke manifold, the kill and choke lines from the choke manifold to the BOP and the cementing lines shall be similarly treated.
2.3.5. Closed Circuit Cooling Systems
All cooling systems shall have anti-freeze added to accept temperatures down to -20 oC.
All exposed seawater-cooled equipment shall be equipped with drainage facilities and should be drained when not in use.
2.3.6. Lubrication and Hydraulic Oil
Lubrication and hydraulic oils shall be changed before the winter season to types suitable for arctic conditions. To prevent increased viscosity problems, a low temperature tolerant oil should be used.
2.3.7. Engines
All engines not in daily use shall be operated at least once a day during the coldest periods. The diesel fuel should be kept free of water contamination and at above 0oC.
3 High Wind
High winds can cause the following hazards:
3.1 Wind speeds higher than 20 knots:
- Movement of unsecured items.
- Dislodging of materials.
- Damage to cladding, light equipment and structures.
3.2 Wind speeds 40-60 knots:
- Damage to crane.
3.3 Wind speeds higher than 60 knots:
- Operational limits reached.
Therefore under these wind conditions the following shall be taken:
3.4 Wind speeds higher than 20 knots:
- Secure loose items.
- Use nets on skips etc.
3.5 Wind speeds 40-60 knots:
- Limit external movements of personnel to Leeward areas (For wind speed higher than 50 knots.).
- Suspend crane operations.
3.6 Wind speeds higher than 60 knots:
- Restrict work access in all high risk areas.
- Secure operations in progress, indoor working only (For wind speed higher than 80 knots.)
Note: There are no restrictions to skidding of the drilling mast with maximum set back load with regards to wind speed.