Section 14 — Equipment Protection & Package Units
Winterization
IPE Engineering Practice IPE-EP-14-1-1
Document number: IPE-EP-14-1-1 · Section: 14 — Equipment Protection & Package Units
SCOPE
- This Practice covers mandatory requirements for protection of equipment, piping, and instruments against the effects of ambient temperature, including hydrate formation, condensation, viscosity change, pour point suppression, and icing.
- Detailed requirements for steam heating of instruments are covered by EP 12-1-1. Requirements for the design, layout and fabrication of steam tracing are covered in EP 5-6-8.
- An asterisk (*) indicates that a decision by the Owner or the Owner's Engineer is required or that additional information is provided by the Purchaser.
- Any deviation from this Practice must be approved by the procedure described in EP 1-1-3.
2.0 REFERENCES
The latest edition of the following standards and publications are referred to herein.
| Engineering Practices | Engineering Practices |
|---|---|
| EP 1-1-3 | Deviations to Engineering Practices |
| EP 5-6-2 | Piping for Rotating Equipment |
| EP 5-6-7 | Steam Traps |
| EP 5-6-8 | Steam Tracing |
| EP 12-1-1 | Control Systems |
DEFINITIONS
- Contractor - Company or business that agrees to furnish materials or perform specified services at a specified price and/or rate to the Owner.
- Inspection - An activity to check that design, materials, fabrication, and testing comply with the requirements of the specification.
- Manufacturer - The recipient of a direct or indirect purchase order for materials and/or equipment. In this context, a direct order is one issued to a Manufacturer by a Contractor or the Owner. An indirect order is one issued to a Manufacturer by a vendor (recipient of a direct order) for materials, fabricated components, or subassemblies.
- Owner - Refining Company.
- Owner's Engineer - A Refining Company appointed engineer.
- Purchaser - The party placing a direct purchase order. The Purchaser is the Owner's designated representative.
- Winterizing - includes such administrative and design procedures as:
- Protective external heating by tracing (steam or electric) or jacketing (steam or hot water)
- Application of insulation
- Elimination of dormant sections of piping
- Maintaining a partial flow in dormant sections of piping
- Draining and flushing
- Agitation
- Providing suitable housing
- Use of antifreeze solutions
- Placing equipment or piping underground
GENERAL GUIDELINES
- The purpose of protective steam heating is to prevent freezing of water or congealing of process fluids in piping, pump, vessels, instruments and other equipment.
- Equipment shall be winterized to prevent interruption of plant operation or failure due to the effects of varying ambient temperature conditions.
- Except for instruments, winterizing with heating should not be used where other means can be used.
- Insulation alone may be used to prevent solidification or increase in viscosity where the liquid in the equipment has sufficient sensible heat for normal operating flow rates and will be drained during shutdown.
- Process, utility, and other equipment shall be winterized when any of the following conditions apply to the fluids contained:
- The Viscosity at the lowest ambient temperature is so high that one-half of the normal flow rate cannot be obtained with the pressure available for starting circulation.
- Ice or hydrate formation occurs due to the pressure reduction of moisture-bearing gases.
- Corrosive compounds form if condensation occurs.
- Undesirable separation or freezing occurs at the lowest ambient temperatures.
- The pour point or freezing point is above the lowest ambient temperature.
CLIMATIC ZONES
- Climatic zone classifications referred to in this Practice are as found in Table 1.
- Facilities shall be winterized in accordance with the specified zone classification and specified environmental and process conditions per paragraphs indicated in Table 2.
REQUIREMENTS FOR ALL CLIMATIC ZONES
Process Piping
- Compressor suction lines between the knockout drum and the compressor shall be heat traced and insulated if the ambient temperature is below the dew point of the gas at the compressor suction or if handling hydrocarbon gas components heavier than ethane. (See EP 5-6-2 for specific requirements of centrifugal and reciprocating compressor suction piping.)
- Intermittently used process piping containing liquids such as tars or chemicals, which will congeal during nonflowing conditions, shall be provided with valves for venting and draining, blowing out with air or nitrogen, or flushing with light stock in preference to heat tracing.
- Tank car and tank truck loading lines shall be heat traced and insulated, and provided with valved flushing or blow out connections.
NOTE: Blowing out piping with air shall be confined to lines containing stocks of low volatility which are well below their flash points. Where piping to be blown discharges into tankage, venting capacity shall be provided to prevent pressurizing the tankage.
Pressure Relieving Systems
Pressure relieving systems, including pressure relief valve bodies, shall be heat traced where the inlet and outlet lines, of pressure relief (PR) devices, may become plugged due to wax deposits or the congealing of viscous fluids at ambient temperatures.
Closed Drain Headers
Closed drain headers shall be winterized where piping may become plugged due to:
- Wax deposits
- Congealing viscous fluids
- Auto-refrigerated releases to the system, such as flashing propane, which may cause freezing in the line.
Instruments and Associated Piping
- Preferred practices are insulating, heat tracing, and heated instrument housings (if required). The instrument mechanism and indicator portions of the transmitters shall be kept within the Manufacturer's recommended temperature rating.
- Instrument piping shall be winterized by sealing with an anti-freeze solution, where possible. Protective heating of lead lines shall be installed in a manner that will prevent the liquid from overheating and boiling away.
- Locally mounted pressure gages and instruments, and seals required for corrosion protection, shall be winterized, if the seal or process fluid would freeze, congeal or be damaged at low ambient temperatures.
Analyzer Shelters
Enclosed walk-in type analyzer shelters shall be heated if the ambient temperature can drop below 41°F.
Process Vessels
- Process vessels containing fluids which may congeal during dormant periods, shall be insulated and, if necessary, heat traced.
- Heat exchangers containing liquids that may congeal or freeze at ambient temperature shall be capable of being drained when not in service.
- Evaporators in chlorine service shall be housed in a heated, forced ventilated building, if the ambient temperature can drop below 55°F.
Machinery and Associated Piping
- Pumps and associated piping shall be protected as required by the nature of fluids handled and duration of anticipated non-operating periods. Circulating fluid from an active pump through a non-operating pump is a preferred practice for pumps handling viscous fluids.
- Seal and flushing oil piping shall be steam traced whenever cooling to the ambient temperature would diminish the quantity or pressure of seal oil at the point of consumption below the equipment Manufacturer's recommended minimum.
Piping
- Underground water systems (including sewers) shall be installed a minimum of 1 foot below the frost line. Above-ground portions of the water systems shall be winterized by such means as heat tracing or draining components of the system after each use.
- All piping in salt-water service, if heat traced, shall be cement-lined.
Hydrants, Monitors, Spray and Deluge Systems
- Self-draining provisions shall be incorporated for fire hydrants used on underground piping. Monitors and hose reels shall be installed with self-draining or manually operated valves for above-ground piping and underground piping above the frost line.
- Spray and deluge systems shall be drained through manually operated valves located at the main operating valve.
Emergency (Safety) Showers
- Heat tracing for winterizing piping to safety showers shall be thermostatically controlled electric heating.
- Steam tracing shall not be used for piping to safety showers.
Flare Seals
Seal legs, the bottom of flare stacks, and seal drums shall be heat traced and insulated or steam injection shall be used to prevent freezing of the water seal.
Vents for Fixed Roof Tanks
Pressure-vacuum vents for cone roof tanks shall be provided with non-freezing features.
Chemicals and Supplies
Chemicals and supplies shall be stored at a temperature above their freezing point, unless other storage temperatures are specified.
Lines Between Seal Drum and Flare
These lines shall be traced and insulated if specified.
Additional Requirements
- Additional requirements for Zone 2 only are detailed in Section 7.O of this Practice.
- Additional requirements for Zone 3 are detailed in Sections 7.O and 8.O of this Practice.
ADDITIONAL REQUIREMENTS FOR ZONES 2 AND 3
Piping
- Exposed sanitary sewer piping shall be winterized by insulating or, if necessary, by heat tracing.
- In live and exhaust steam systems, dead legs and low points where condensate may collect shall be provided with a steam trap per EP 5-6-7.
- Drain valves shall be provided in utility air system strainers, traps, and low points in the piping where moisture may collect.
- Drains shall be provided at all low points of above-ground piping in water service.
- In water service, block valves and check valves installed in vertical piping shall be furnished with body drains to ensure maximum draining when the valve is shut.
- Closed drain headers shall be winterized.
Instruments
- Electronic Instruments which may be damaged by freezing shall be installed in heated housing or located in buildings to maintain the temperature within the Manufacturer's recommended temperature rating.
- Enclosed analyzer cabinets shall be heated.
Process Vessels
Where hydrocarbon and water are separated in a vessel, only those parts of the vessel containing water need be protected from freezing. Insulation or heat tracing may be used as appropriate.
Machinery and Auxillaries
- Compressors, turbines, engines, and other major machinery (including auxiliaries) not installed in heated buildings require winterizing. Exposed components such as cooling water lines, cooling jackets, lube and seal oil piping, filters, compressor suction lines, and knockout drums shall be winterized for normal operation and for shutdown conditions.
- Compressors and auxiliaries enclosed in buildings shall have winterizing protection when the system is shut down.
- Pumps in intermittent service such as firewater or fill and discharge to oil storage tanks, shall have protective heating and insulation or shall be installed in a heated enclosure if the liquid handled will freeze or become too viscous to pump.
ADDITIONAL REQUIREMENTS FOR ZONE 3 ONLY
Piping for Water Service
- Block valves in water service, at branch takeoff connections to piping and equipment, shall be protected by one of the methods listed below if the branch piping may be shut down while the remainder of the unit is in operation:
- Locate in a Valve Box packed with insulation
- Locate in a heated Valve Box
- Heat trace the valve
- Sections of piping systems located above the frost line shall be provided with drains, and if necessary, shall be insulated or heat traced, or both.
- Underground piping in water service, subject to frost upheaval or sudden temperature change shall be carbon steel.
- Open-sight drains from pumps and compressors shall be piped to sewer, sloped continuously downward where possible. If traps or surface seals are used, they shall be protected against freezing.
UtilIty Stations
Lateral connections to utility stations (air, water, or steam) shall have a valve at the header and a drain valve on the station branch.
Instruments
Winterizing of locally mounted instruments shall be provided by means of insulated housings with steam coils or electric heating. Heating shall be installed in a manner to avoid hindering removal of the instruments and be within the Manufacturer's recommended temperature rating.
TABLE 2
WINTERIZATION REQUIREMENTS BY ZONE
| EQUIPMENT TO BE WINTERIZED | ZONE 1 | ZONE 2 | ZONE 3 |
|---|---|---|---|
| PARAGRAPH | PARAGRAPH | PARAGRAPH | |
| PIPING Compressor Suction Lines Process Piping (Intermittently Used), Containing Liquids Pressure Relieving Systems Closed Drain Headers Emergency Showers Below-Ground and Fire Water Systems Exposed Sanitary Sewer Piping Live and Exhaust Steam Systems Utility Air Systems Above-Ground Water Lines Block Valves in Water Lines to Process Equipment All Process Piping Above Frost Line Water Drains for Pumps and Compressors Utility Station Piping Laterals Lines Between Seal Drum and Flare |
6.1.1 6.1.2 , 6.1.3 6.2 6.3 6.1O.1, 6.1O.2 6.8.1, 6.8.2 6.14 |
6.1.1 6.1.2, 6.1.3 6.2 6.3, 7.1.6 6.1O.1, 6.1O.2 6.8.1, 6.8.2 7.1.1 7.1.2 7.1.3 7.1.4, 7.1.5 6.14 |
6.1.1 6.1.2, 6.1.3 6.2 6.3, 7.1.6 6.1O.1, 6.1O.2, 8.4 6.8.1, 6.8.2, 8.1.1, 8.1.3 7.1.1 7.1.2, 8.2 7.1.3, 8.2 7.1.4, 7.1.5 8.1.1 8.1.2 8.1.4 8.2 6.14 |
| INSTRUMENTS Instrument Bodies (or Portions Containing Fluids) Instrument Piping Pressure Gauge and Instrument Seals Electronic Instruments Analyzers Local Instruments |
6.4.1 6.4.2 6.4.3 6.5 6.4.3 |
6.4.1 6.4.2 6.4.3 7.2.1 6.5, 7.2.2 6.4.3 |
6.4.1 6.4.2 6.4.3 7.2.1 6.5, 7.2.2 6.4.3, 8.3 |
| PROCESS VESSELS Vessels Containing Fluids Which May Congeal Heat Exchangers (Shell and Tube, Air Cooled) Chlorine Evaporators Vessels Containing Water |
6.6.1 6.6.2 6.6.3 |
6.6.1 6.6.2 6.6.3 7.3 |
6.6.1 6.6.2 6.6.3 7.3 |
TABLE 2
WINTERIZATION REQUIREMENTS BY ZONE (CONTINUED)
| EQUIPMENT TO BE WINTERIZED | ZONE 1 | ZONE 2 | ZONE 3 |
|---|---|---|---|
| PARAGRAPH | PARAGRAPH | PARAGRAPH | |
| PUMPS AND MACHINERY | 6.7.1 6.7.2 |
6.7.1, 7.4.3 6.7.2 7.4.3 7.4.1, 7.4.2 |
6.7.1, 7.4.3 6.7.2 7.4.3 7.4.1, 7.4.2 |
| Pumps (Including Associated Piping) Seal, Flushing, and Lubricating Oil Lines Pumps in Intermittent Services Major Machinery (such as Compressors, Turbines, Including Auxiliaries) |
6.7.1 6.7.2 |
6.7.1, 7.4.3 6.7.2 7.4.3 7.4.1, 7.4.2 |
6.7.1, 7.4.3 6.7.2 7.4.3 7.4.1, 7.4.2 |
| MISCELLANEOUS | 6.1.3 6.11 6.12 |
6.1.3 6.11 6.12 |
6.1.3 6.11 6.12 |
| Chemicals and Supplies Seal Legs, Bottom of Flare Stacks, and Seal Drums Pressure Vacuum Vents |
6.1.3 6.11 6.12 |
6.1.3 6.11 6.12 |
6.1.3 6.11 6.12 |
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