Page 46: of Offshore Engineer Magazine (Nov/Dec 2014)

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their approach to winteriza- Limit the use of systems designed to • tion. Adopting a “heat trace prevent or remove sea ice forming everything” approach will be around equipment and walkways. uneconomic. Possible solu- When seas are frozen, there will be

EPIC tions include: no sea spray to blow up on deck. Sea •

Accommodating short spray is only expected when wind periods of downtime and speeds exceed 10m/s. However the therefore circumventing the potential for atmospheric ice and snow 100-year minimum design may need to factored in.

• temperature, reducing Install waste heat recovery units to

CAPEX. Equipment must generation trains and recycle exhaust be specifed to survive such from HVAC systems.

shutdowns without causing

Ofshore Energy Tier II Compression Project, Ofshore

Naturally ventilating, partial or fully damage.

Nova Scotia. Photo from SNC-Lavalin enclosed module design

Installing smart heat tracing • control systems capable of minimizing equipment remains heat traced whilst Det Norske Veritas (now part of the DNV power demand by factoring in wind the sheltered side may be left unpro- GL group) recently issued the Offshore speed and direction - the cold face of tected, reducing OPEX. Standard for Winterisation for Cold

Climate Operation, DNV-OS-A201. DNV acknowledges that problems encountered Naturally ventilated or enclosed? in polar operations cannot be easily

Naturally Ventilated Enclosed / Modularized solved by prescriptive instruction and now favor a more functional approach to

Human Cold weather conditions can An enclosed module can be heated to engineering design. The key is preparing factors stop or reduce the amount of a comfortable level whereby opera- time operators are permit- tors can work a complete shift wearing a detailed winterization philosophy early ted to maintain and inspect minimal restrictive cold weather PPE.

in the design process. It should be agreed equipment. Routine maintenance and inspection between the operator and contractor and

Low frequency maintenance can be carried out more easily, mini- cascaded through to the equipment and or inspection can increase mizing the risk of potential equipment heat tracing suppliers.

the potential for hydrocarbon failure or hydrocarbon leakage.

Equipment layout and modularization leakage.

is a key decision. It is sensible to locate

Hydrocarbon Detection of gas is possible, Detection should be quicker with gas safety and process critical equipment gas leak however, if the gas is dissi- detection within each module and/or inboard, where the brunt of the wind pated by the wind it may not HVAC exhaust.

and weather will be least felt. Shielding be so quick to detect.

the equipment from the elements may

Leaked The concentration of gas may Gas will mix with HVAC air and create however be contrary to allowing leaked gas ignites remain low enough to prevent a highly explosive environment within

PROVIDING THE hydrocarbons to escape safely and (explosion) explosion as the deck is natu- the container.

swiftly. Conventional designs are self-

VITAL CONNECTION rally ventilated. If concentrations increase and the venting, where the process decks are

HVAC shuts down, the gas can poten- tially displace the oxygen to such open to the environment on all sides. an extent that the explosion risk is

But, this approach focuses on mitigat- removed. The environment within the ing the risk associated with leaked container will however be extremely gas and does not consider the human hazardous when the HVAC is reintro- factors involved with operation and

Reliable power and duced to exhaust the retained gas maintenance.According to NORSOK, from the area.

control. the percentage of time that an individual

Explosion Air supply all around to If the HVAC system shuts down as employee is exposed to a wind chill initiates a maintain the fre until the fuel designed the fre should snuf itself index (WCI) above 1000W/sq m should

Integrity in every subsea fre source is removed. out as the oxygen is used up.

be reduced as far as reasonably practica- umbilical and cable design,

HVAC Not necessary. Walkways will Each enclosed module will require ble. For arctic installations, outdoor oper- however require ice preven- HVAC, providing a comfortable work- ations should be identifed and reduced manufacture and delivery. tion heat tracing. ing environment for the operator.

to a minimum. Shielding workers from

Number of Less line connections neces- More fanged connections between the wind will have a dramatic impact on interstitial sary across the platform modules and therefore potential leak their availability to carry out work.

connections therefore reducing the num- paths.

Equipment inspection and planned / ber of potential leak paths.

unplanned maintenance will be easier if

Emergency Open decks provide quick and Potentially hampered by multiple equipment trains are enclosed or semi- exit routes easy access to muster points blast doorways and airlocks etc. enclosed in heated modules. Conversely,

WWW.JDRGLOBAL.COM UNITED KINGDOM • UNITED STATES • THAILAND • SINGAPORE • MALAYSIA • GERMANY • BRAZIL with minimal obstructions. Winterizing the walkways within the modules will inevitably require more

Winterization will be neces- modules will not be necessary.

inter-connections as pipework will need sary to ensure walkways are to pass between bulkheads. So while free from ice.

enabling more time for maintenance,

November 2014 | OE oedigital.com 48 046_OE1114_EPIC2_SNC.indd 48 10/21/14 5:11 PM