ASSIGNMENT SHEET

INFORMATION SHEET

BOILER AND CONDENSER LAY UPS

Information Sheet Number 62B-232

INTRODUCTION

Preventing corrosion of boilers and condensers prolongs the useable life of the equipment. Corrosion or rust degrades equipment as fast as it does your automobile if not properly maintained. Lay ups are the boilers and condensers protection from the elements.

REFERENCES

(a) Condensers, Air Ejectors and Heat Exchangers NSTM Chapter 254

(b) Boilers NSTM Chapter 221

(d) Pollution Control NSTM Chapter 593

INFORMATION

A. Boiler entry precautions are critical to reduce the possibility of boiler damage and danger to personnel. The following precautions shall be observed whenever a boiler is being drained, opened and entered.

1. While personnel are working in the boiler interior, a person shall be stationed outside to render assistance in case of an accident.

2. Warning signs calling attention to the fact that personnel are working in the boiler shall be placed at the top watch station in the fireroom, and the sign shall not be removed until it is determined that work has been completed and personnel are clear of the secured boiler.

3. Before sending personnel into the boiler, allow it to air out thoroughly. Because of the possible presence of flammable or noxious vapors, the gas‑free engineer shall approve entry into the boiler. Special precautions shall be taken to ensure an adequate supply of fresh air in a secured fireroom if the boilers in that fireroom are connected to the same stack as the steaming boilers in another fireroom. Unless a ship is equipped with division plates that provide an individual gas passage to the top of the stack for each boiler, no work shall be done on boilers connected to the same stack as steaming boilers if the work involves opening the uptake doors or furnace doors.

4. The use of a non-explosion proof lights in an open boiler is prohibited in firesides or watersides. Portable electric lights may be used, but the use of hand flashlights is preferable. If portable lights are used in a boiler, the electric leads shall be thoroughly insulated, and the portable lighting fixture shall be of the explosion‑proof and watertight type. This type has a substantial glass globe around the light bulb and a guard around the globe. As a safety precaution, electrical equipment and portable receptacles used to supply power for work within a boiler shall be tested according to Electric Plant General NSTM Chapter 300.

5. When a boiler is to be entered by personnel, all valves shall be wired shut and tagged in accordance with tag out procedures. This prevents the accidental admission of steam or water into the boiler. Remote valve actuating gear shall be included in this precaution. On steam lines containing two valve protection, open the drain valve located in a branch between the isolation valves. The isolation and shutoff valves connecting the dead boiler with live systems shall be secured, blanked if possible, and tagged, indicating that personnel are working in the secured boiler. The tags shall not be removed or valves opened until it is determined that work has been completed and workers are clear of the secured boiler. NOTE: Remember that openings in systems > 150 psig will be protected by two valves unless the Commanding Officer's authorization is obtained.

6. Steam or hot water may leak into an idle or open boiler through a leaky bottom blow valve sharing a common line with the blowdown valves of another boiler or the main steam stop, auxiliary steam stop, main feed stop valves, and superheater high pressure drain valves. Open the superheater bilge drain valves will be open to permit drainage of any water leaking into headers. If pressure is to be applied to any valve on an open boiler, no personnel shall be allowed in the boiler until pressure has been applied to the valve and its tightness has been positively assured. Special precautions are required in checking the tightness of boiler blowdown and guarding valves of an open boiler that has a common boiler blow connection with a steaming boiler. To ensure the tightness of the valves on the open boiler, the steaming boiler shall be blown down before personnel are permitted to work on the open boiler, to ensure the valves on the open boiler are closed tightly and seated.

7. Drain connections to the atmosphere on all dead interconnecting piping shall be opened for visual observation of drainage.

8. Wire and danger tag in the closed position the valves to the steam smothering system while personnel are working in the vicinity and remove wire and danger tags when the work is finished.

9. The use of ordinary hose shall not be permitted for the wet method of laying up idle boilers. Use only an approved and clearly marked hose to prevent contamination.

B. Boiler watersides will begin to corrode as soon as they are exposed to the atmosphere or to water containing oxygen. For this reason a secured boiler that will not be lighted off within 24 hours should be properly laid up as soon as possible. If a boiler is to be lighted off within 24 hours of being secured, the residual pressure in the secured boiler after bottom blowdown shall be maintained as long as possible. Align the steam blanket if pressure drops below steam blanket supply pressure. Boilers secured for more than 24 hours shall be laid up using an approved method. The primary consideration of idle boiler maintenance is the prevention of oxygen corrosion of the boiler metal. Wet iron exposed to oxygen will corrode. Elimination of the corrosion of the iron can be accomplished by removing either the air or the moisture.

C. The method of idle boiler lay up chosen depends on considerations such as maintenance or repair work scheduled, planned duration of lay up, effectiveness of the lay up method, availability of support for the lay up method, and boiler recovery time. With a cold boiler it takes approximately 2½-3 hours minimum to light off and bring it to operating pressure. Lighting off from a steam blanket lay up takes approximately 1½-2 hours minimum to be at operating pressure. If done faster, could cause damage from thermal shock. The following is a description of boiler wet lay up methods and time limitations.

1. The steam blanket lay up method uses 150 psig steam from the 150 psig desuperheated steam system or shore source steam that meets specifications outlined in NSTM chapter 220 V2. This provides reasonable protection for the boiler watersides, firesides and superheater but, does not provide protection for the economizer. This lay up is applied as soon as residual steam pressure has dropped below steam blanket supply pressure. The steam keeps the boiler warm and requires no special preparation to get the boiler underway ready. A steam blanket lay up is limited to thirty days. At the end of thirty days, the boiler must be placed on a hydrazine wet lay-up or a dry type lay-up if not lighted off.

2. The nitrogen blanket lay up uses one or more compressed nitrogen gas bottles connected to the boiler through a regulator and small piping system. The regulator is adjusted to maintain 5 psig constant pressure on the boiler to keep oxygen out. This provides reasonable protection for the boiler watersides and superheater, but does not provide protection for the economizer. This lay up is applied when residual steam pressure is at or below 5 psig. Since the boiler is cold, heat should be applied to the firesides to protect them from corrosion. This lay up requires no special preparation to get the boiler underway ready. A nitrogen blanket lay up is limited to thirty days. At the end of thirty days, the boiler must be placed on a hydrazine wet lay-up or a dry type lay-up if not lighted off.

3. Operating ships may interrupt steam or nitrogen blanket pressure to perform emergent repairs. Such maintenance should be performed as close to scheduled boiler light‑off as possible to minimize oxygen corrosion. The interruption of steam or nitrogen blanket pressure shall only be done once per lay‑up period. The time the steam or nitrogen blanket pressure is interrupted should be minimized as much as possible and shall not exceed 8 hours. The 8 hour period begins when the lay up pressure falls to atmospheric. If extensive maintenance or repairs are required, the boiler should be placed on a dry lay up.

4. The hot deaerated fill lay up provides fair protection for boiler watersides and economizer. There is no protection for firesides unless heat is applied. The hot deaerated fill lay up requires a deaerating feed tank (DFT) to be in operation to keep deaerated feedwater available to backfill the boiler. The boiler is filled through the superheater backfill connection after bottom blow is completed and residual steam pressure falls to 15 psig. The boiler has to be filled completely and all air expelled.An approved steam hose must be used to connect from the superheater backfill connection to the supply to protect personnel from the hot deaerated feedwater. A constant pressure must be maintained on the boiler by a head tank or pump not to exceed 150 psig. If the boiler has a stainless steel superheater and is not equipped with a superheater backfill connection the boiler must be dumped before filling the boiler through the economizer. This prevents chloride contamination of the superheater. This lay up requires no special preparation for light off and is limited to fourteen days. At the end of fourteen days, the boiler must be placed on a hydrazine wet lay-up or a dry type lay-up if not lighted off.

5. The Hydrazine/morpholine lay up for coordinated phosphate (COPHOS) treated boilers can only be applied by an industrial activity. This lay up is applied at any time when the boiler is secured and at 0 psig. This lay up requires the boiler to be completely filled and all air expelled. A constant pressure must be maintained with the use of a head tank or pump. Preparation for light off requires a portion of the Hydrazine/morpholine to be drained and properly desposed of in accordance with pollution control NSTM Chapter 593. This lay up has no time limit.

a. Ship's force can apply this lay up for boilers under the CHELANT treatment system. Protection and application are quite different for COPHOS treated boilers. This lay up requires the boiler to be completely filled and all air expelled. A constant pressure must be maintained with the use of a head tank or pump. Preparation for light off requires a portion of the hydrazine/morpholine to be drained and properly deposed of in accordance with pollution control NSTM Chapter 593. This lay up also has no time limit.

6. The Sodium nitrate lay up provides excellent protection to the boiler watersides and economizer. There is no protection for firesides unless heat is applied. This lay up is for boilers under the COPHOS treatment system. It requires the boiler pressure to fall to 0 psig and to be dumped and filled with sodium nitrate treated water until all air is expelled. A constant pressure must be maintained with the use of a head tank or pump. The amount of sodium nitrate used varies by boiler capacity, follow the procedures in boilers NSTM Chapter 221. Preparation for light off requires the boiler and associated systems to be dumped and flushed to remove all sodium nitrate. The sodium nitrate treated water must be disposed of in accordance with Pollution Control NSTM Chapter 593.

a. Operating ships using the CHELANT treatment system shall not use sodium nitrate for wet lay up, prior to dry lay up or during routine hydrostatic testing. Sodium nitrate and hydrazine are incompatible. Hydrazine is one of the chemicals used in the CHELANT treatment system. The boiler must be completely drained of all hydrazine treated water prior to using sodium nitrate. An intermediate maintenance activity or industrial activity is authorized to use sodium nitrate on CHELANT treated boilers for water jet, hydro, and wet lay up.

b. Sodium nitrate treated boilers must be dumped and flushed with feed quality water to remove residual sodium nitrate prior to applying CHELANT treatment or hydrazine/morpholine lay up.

D. Dry lay up methods are used when boiler watersides are to be opened for long term inspection or repair. There are two dry lay up methods that can be used and the preliminary procedures are the same for each method. Dry lay up methods provide reasonable protection for boiler watersides, economizer and firesides provided the boiler is completely dried out after dumping. Both methods have no time limit. The following is a description of boiler dry lay up methods.

1. When the boiler pressure has dropped to 100 psig it is treated with sodium nitrate and filled to the top of the boiler gage glass. When filling, the boiler water level shall be observed closely to avoid overfilling and contaminating the superheater with chlorides and boiler chemicals. The amount of sodium nitrate used varies by boiler capacity, follow the procedures in Boilers NSTM Chapter 221. When boiler pressure has dropped to 0 psig dump the boiler and dispose of sodium nitrate treated water in accordance with Pollution Control NSTM chapter 593. After the boiler is thoroughly drained and opened it must be completely dried out. Starting from the top of the boiler using low pressure air to blow out all accessible surfaces including all boiler tubes, drums and headers. Do not contaminate the boiler with wet or oily low pressure air. Thoroughly inspect all waterside surfaces to ensure they are dry, then apply one of the following lay up methods:

a. Hot air lay up method uses an electric heater and blower to circulate hot air through the boiler watersides and firesides as long as the boiler is idle. This requires all accesses to be closed with the exception of the hot air entry and exit point. Special adapters are needed to attach the blower connections to the boiler.

b. Desiccant lay up method uses bags of desiccant to keep the boiler dry. The amount of desiccant used varies by boiler capacity. Follow the procedures in Boilers NSTM Chapter 221. The bags are evenly distributed through all boiler drums, headers and the economizer. A count of bags is made as they enter the boiler and the count is logged in the engineering log when removed. Humidity cards are placed inside the boiler to indicate when the bags need to be changed. The boiler is then closed up. It is recommended to have plexiglass covers made to fit the boiler steam and water drum accesses so that humidity cards can be observed easily.

E. Preparation for light off can vary in time depending on boiler integrity and repairs. Remove the desiccant or hot air blower connections, clean all gasket matting surfaces as required and close the boiler. Flush the boiler by refilling the economizer and superheater with feed‑quality water and dumping. Do not light‑off with sodium nitrite solution in the boiler. Sodium nitrite adversely affects water chemistry in a steaming boiler. Refill the boiler and conduct a hydrostatic test accordance with boilers NSTM chapter 221.

1. The dry lay up procedures for CHELANT treated boilers are the same except treating the boiler with sodium nitrate and flushing is not required for boilers on the CHELANT treatment system. These procedures are omitted.

F. Documentation and monitoring the boiler's lay up is the responsibility of the cold iron watch or messenger and the Oil king. The cold iron or messenger watch will record the status of the boiler lay up. The oil king shall log lay up status daily and any test performed on the boiler and entries made in the boiler water chemistry worksheet/log in accordance with boilerwater/feedwater test and treatment NSTM Chapter 220 V2 and boilers NSTM Chapter 221.

1. Boilers using hydrazine/morpholine lay up shall be tested by the oil king on the first day of lay up and weekly thereafter for hydrazine.

2. The head tank level or boiler pressure shall be monitored and logged hourly by the assigned watchstander.

3. Changing from one lay up method to another is authorized only as follows:

a. From steam blanket to nitrogen blanket and vice versa, provided lay up pressure is continuously maintained and the total time of the lay‑up (steam and nitrogen combined) does not exceed 30 consecutive days from securing.

b. From any wet or dry method to hydrazine/morpholine or sodium nitrite lay‑up, with the special restrictions given below:

(1) To prepare for the transition from sodium nitrite wet lay‑up to hydrazine/morpholine lay‑up, dump the boiler, economizer, superheater, and DFT, and drain associated recirculation piping. Flush by refilling the boiler, economizer, superheater, DFT, and associated recirculating piping with feed‑quality water and dumping. Then a hydrazine/morpholine lay up can be applied.

(2) To prepare for the transition from dry lay‑up to hydrazine/morpholine lay‑up, flush the boiler with feed‑quality water and dump. Do not apply hydrazine/morpholine lay‑up with sodium nitrite solution in the boiler or DFT.

c. From any wet lay up to any dry lay up method.

d. From desiccant lay up to hot air lay up and vice versa.

e. From Hydrazine/Morpholine to steam blanket or nitrogen lay up.

G. If a lay‑up is lost, the boiler shall be lighted off within 24 hours or an alternative lay‑up method applied as specified in changing lay up methods. This applies in all cases except desiccant lay‑up, where saturated desiccant can be replaced or dried out.

H. Main and auxiliary condenser lay ups are required to protect the condenser from corrosion. Condensers, air ejectors and heat exchangers NSTM chapter 254 contains the procedures for lay ups. A summary of a condenser lay up is given below:

1. A short term condenser lay up requires the salt water side of main and auxiliary condensers to be filled with salt water, circulated once a day for at least ten minutes using the circulating water pump. If circulation is not accomplished for three or more days in succession, drain and fill the condenser with fresh potable water or feed quality water. This lay up is limited to one week.

2. A mid-term condenser lay up requires the sea water side of the condenser to be drained and immediately filled with fresh potable water or quality feedwater. After an initial two or three weeks, the condenser will be drained and refilled with fresh water. This replaces the stagnant and deoxygenated water. The condenser will then remain full until it is operating. If the condenser is drained, opened, and cleaned it must be refilled with fresh water or placed in operation. For condensers that remain idle the water must be replaced monthly. This lay up is limited to four months.

3. A long term condenser lay up requires the sea water side to be drained, opened, and cleaned. A mechanical cleaning is done with a pressurized water lance or with metallic rods to clean debris or barnacles from the tubes. The condenser is then left dry and can remain this way indefinitely.

4. The steam side of the idle condensers is required to be drained and can remain dry for up to one month. If the condenser is not to be operated for more than one month, it is to be drained as soon as possible after securing and dried out using an electrically heated air blower. The blower shall be discharged into a hotwell opening.

5. The moist air shall be allowed to vent to the atmosphere from an opening in the upper shell of the turbine exhaust casing. After the drying process, secure all condenser openings, and check the condenser weekly and repeat the drying process if any water or moisture accumulates.

I. It is important to keep safety in mind at all times in the handling, stowage, and use of chemicals or electrical equipment. Ensure that all personnel involved follow safety procedures in accordance with boilers NSTM chapter 221, boilerwater/feedwater test and treatment NSTM 220 V2, electric plant general NSTM chapter 300, pollution control NSTM chapter 593, and stowage, handling, and disposal of hazardous general use consumables NSTM chapter 670. There are numerous safety precautions, the following are a few examples:

1. Ensure all electrical equipment is safety checked and in good repair prior to using it to support any repair evolution on boilers or condensers.

2. Sodium nitrite is chemically incompatible with hydrazine. Store these chemicals separately. Do not mix sodium nitrite and hydrazine solutions.

3. Sodium nitrate is an oxidizing agent that may support combustion. Exercise caution in stowing and using this chemical.

4. When handling chemicals always wear the proper protective gear; goggles, face shield, plastic or rubber gloves, rubber apron, respirator or whatever is required by the procedure being performed and the chemical being used. The test and treatment chemicals are a poison having varying degrees of toxicity.