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TYPE OF LAY-UP FOR STAINLESS STEEL PIPINGS
5

TYPE OF LAY-UP FOR STAINLESS STEEL PIPINGS

TYPE OF LAY-UP FOR STAINLESS STEEL PIPINGS

(OP)
CURRENTLY I AM WORKING IN A STAINLESS STEEL PIPING PROJECT FOR THE COOLING WATER SERVICE, I WANT TO KNOW THE METHOD THROUGH WHICH DRY LAY-UP SHALL BE PERFORMED AFTER HYDRO-TEST.
EXPECTING VALID SUGGESTIONS

RE: TYPE OF LAY-UP FOR STAINLESS STEEL PIPINGS

4
A few things.

1) Writing in CAPITALS is normally understood as SHOUTING. Please don't do it again.

2) Dry lay-up?? Can you explain a bit more, this term is not familiar to me.

3) The usual way this site works best is someone comes on, describes their issue with sufficient details, (e.g. line size, length, pressure rating, material etc) often with a diagram or schematic and then says how they are thinking of doing something, or issues they have with a particular technique and request some assistance. Simply appearing to demand answers tends not to go down so well. No one gets paid for answering posts here.

Please try again taking note of the above. Thanks, LI

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: TYPE OF LAY-UP FOR STAINLESS STEEL PIPINGS

You can use this reference as a starting point:

SAES-A-007 Hydrostatic Testing Fluids and Lay-Up Procedures

5.2.3 Dry lay-up
5.2.3.1
Dry lay-up may be achieved using several different drying media. These include hot dry air, controlled dew poit inert gas, and drying chemicals such as glycol or methanol applied between two pipeline scrapers or as a gelled scraper. The best results may be achieved by using a combination of these techniques.
5.2.3.1.1
Dry lay-up using hot or dew point controlled air may only be used for systems where the dew point can be successfully reached within 1 week. Longer drying periods using air may contribute to the generation of excessive quantities of corrosion products in line. Therefore, dry lay-up using air is only appropriate for systems that can be easily dried. One means to assure effective drying within the required time is to limit the length of the system being hydrotested at one time.
5.2.3.1.2
Sweet gas may be used for dehydration. However, before using sweet gas ensure that hydrate formation will not be a problem. Hydrate formation may occur at low temperatures and elevated pressures.
5.2.3.2
Remove the hydrotest water from the system. For facilities other than pipelines, drain the system completely, sweep and mop as required to ensure that no visible traces of water remain. For pipelines, dewatering shall be performed by scraping with a three- or four-cup displacement scraper or better system such as a gelled scraper. Scrapers shall be driven by nitrogen or sweet gas unless the use of dry air has been pre-approved.
5.2.3.3
When seawater or similar high salinity water has been used as the hydrotest media, remove salts from the metal surface by rinsing with a low-salinity water containing less than 4,500 ppm total dissolved solids. For pipelines, use a slug of low salinity water between two scrapers to rinse salts from the walls. The size of the slug will be dependent upon the length of the line. More than two scrapers may be required in cases where a large slug of water is required. Present calculations and assumptions made to justify the size of slug to be used. The use of seawater/high salt hydrotest water in facilities under the responsibility of Pipelines Department must be pre-approved in writing by Pipelines Department, General Supervisor, PTSD, and the responsible area Manager. For equipment that is under the responsibility of other Departments, the use of seawater/high salinity water must be pre-approved in writing by the local corrosion engineer. All mitigation actions shall be presented for approval at design stage prior to commencement of construction or it will not be a permissible option once construction has commenced.
5.2.3.4
If using inert gas drying for a pipeline, first, remove remaining water with a methanol or glycol slug between two scrapers, in order to achieve drying in a short period. Then dry with dehydrated inert gas. Gelled chemicals may also be used. Ensure compatibility of dehydrating chemicals with all materials in the system.
5.2.3.5
If at all possible, hydrotests should be performed with the valves removed from the line. However, if this is not possible, valves must be carefully dewatered. As the final stage of the dewatering process, remove water from pipeline valves and all other valves that may be damaged by trapped hydrotest water by blowing through the top drain with nitrogen and displacing fluid out of the bottom of the valve. Do not open or close valve during this dewatering sequence. When the bulk of the water has been removed, blow vapor phase corrosion inhibitor Cortec VpCI 309 or equivalent with nitrogen until it is visibly discharged at the bottom of the valve.
5.2.3.6
Immediately after dewatering, start drying the system to a dew point that will ensure a dew point of -1°C or less at the final lay-up pressure at all exit points. Dry by blowing sweet gas, nitrogen, or, if pre-approved, heated dry air through the system for not less than 12 hours to allow any remaining moisture to come to equilibrium with the dry air. Check and ensure that all measurement locations are at or below the required dew point. Repeat the drying procedure if the measured dew point at any one location is above the set limit. For pipelines, dew point readings must be done at the beginning, end, and all mainline valve locations. Record the dew point temperature readings at each test location. Record the pressure of the line or system at the time of the dew point measurement. Record the pressure at which the dew point measurement is made if different to the actual system or line pressure. If the dew point temperature is derived at a different pressure to the lay-up pressure, use Appendix 2 or equivalent conversion charts to yield the dew point at lay-up pressure.
5.2.3.7
When the required dew point is reached, pressurize the system with nitrogen or sweet gas to the final lay-up pressure. Dry air may be used only if it has been pre-approved. The system shall be maintained at a positive pressure of at least 30 psig unless this exceeds the design pressure of the system. Pressures up to the normal operating pressure have been used for lay-up for some systems. The dew point at the final lay-up pressure must be lower than -1°C.
5.2.3.8
Shut in the system, maintain and monitor the pressure per 5.2.2.4 during the lay-up period.
5.2.3.9
For pipelines, re-measure the dew point at all original test locations one week after reaching final lay-up pressure. If any dew point reading is found to be higher than -1ºC at the lay-up pressure, then the entire line must be dried again or an alternative preservation method must be implemented.
6
Stainless Steel Equipment
6.1
Type 300-series stainless steels shall be tested only with water that has very low chloride content in order to avoid pitting and stress corrosion cracking. The maximum allowable chloride concentration is 50 ppm. Verify the quality of the water following the requirements of Paragraph 4.2.
Exceptions:

Type 300-series stainless steel valve trim shall not be a sufficient sole criterion for classifying a carbon steel system as "stainless" for the purpose of applying Section 6. For example, this section shall not apply to carbon steel pipelines with valves having stainless trim unless there are also other stainless steel components included.

In special cases, with the prior written approval of the Supervisor, CTU/ME&CCD/CSD, water of up to 250 mg/liter chloride ion is permitted, provided:
(a) that the hydrostatic test period is less than four days,
(b) that the system is rinsed with steam condensate or demineralized water until the effluent chloride content reaches below 50 mg/liter, and
(c) that the system is completely drained immediately after hydrostatic test and rinse.
6.2
Type-400-series stainless steels are highly prone to atmospheric corrosion. Type 400-series stainless steel trimmed valves shall be removed from pipelines before hydrotest. If it impossible to remove such valves from the line, then written hydrotest procedures must be prepared and approved ahead of time allowing the valves to remain in place. When equipment containing any Type-400 series stainless steels is left in place, it shall be hydrotested in accordance with the requirements of Paragraph 6.3, 6.4, and 6.5 of this standard. The hydrotest procedure shall carefully detail measures prevent corrosion including lay-up of the equipment. Do not use ambient lay-up for equipment made of 400-series stainless steels.
6.3
Treat the hydrostatic test water with oxygen scavenger per paragraph 5.1 if the equipment contact time with water might exceed 4 days.
6.4
Lay-up the system following the requirements of Paragraph 5.2.
6.5
At the end of the lay-up, commission and start up the stainless steel equipment within 14 days. Remove the hydrotest water from the system. For facilities other than pipelines, drain the system completely, sweep and mop as required to ensure that no visible traces of water remain. For pipelines, dewatering shall be performed by scraping with a three- or four-cup displacement scraper or better system such as a gelled scraper. Scrapers shall be driven by nitrogen or sweet gas unless the use of dry air has been preapproved.
5.2.3.3
When seawater or similar high salinity water has been used as the hydrotest media, remove salts from the metal surface by rinsing with a low-salinity water containing less than 4,500 ppm total dissolved solids. For pipelines, use a slug of low salinity water between two scrapers to rinse salts from the walls. The size of the slug will be dependent upon the length of the line. More than two scrapers may be required in cases where a large slug of water is required. Present calculations and assumptions made to justify the size of slug to be used. The use of seawater/high salt hydrotest water in facilities under the responsibility of Pipelines Department must be preapproved in writing by Pipelines Department, General Supervisor, PTSD, and the responsible area Manager. For equipment that is under the responsibility of other Departments, the use of seawater/high salinity water must be preapproved in writing by the local corrosion engineer. All mitigation actions shall be presented for approval at design stage prior to commencement of construction or it will not be a permissible option once construction has commenced.
5.2.3.4
If using inert gas drying for a pipeline, first, remove remaining water with a methanol or glycol slug between two scrapers, in order to achieve drying in a short period. Then dry with dehydrated inert gas. Gelled chemicals may also be used. Ensure compatibility of dehydrating chemicals with all materials in the system.
5.2.3.5
If at all possible, hydrotests should be performed with the valves removed from the line. However, if this is not possible, valves must be carefully dewatered. As the final stage of the dewatering process, remove water from pipeline valves and all other valves that may be damaged by trapped hydrotest water by blowing through the top drain with nitrogen and displacing fluid out of the bottom of the valve. Do not open or close valve during this dewatering sequence. When the bulk of the water has been removed, blow vapor phase corrosion inhibitor Cortec VpCI 309 or equivalent with nitrogen until it is visibly discharged at the bottom of the valve.
5.2.3.6
Immediately after dewatering, start drying the system to a dew point that will ensure a dew point of -1°C or less at the final lay-up pressure at all exit points. Dry by blowing sweet gas, nitrogen, or, if pre-approved, heated dry air through the system for not less than 12 hours to allow any remaining moisture to come to equilibrium with the dry air. Check and ensure that all measurement locations are at or below the required dew point. Repeat the drying procedure if the measured dew point at any one location is above the set limit. For pipelines, dew point readings must be done at the beginning, end, and all mainline valve locations. Record the dew point temperature readings at each test location. Record the pressure of the line or system at the time of the dew point measurement. Record the pressure at which the dew point measurement is made if different to the actual system or line pressure. If the dew point temperature is derived at a different pressure to the lay-up pressure, use Appendix 2 or equivalent conversion charts to yield the dew point at lay-up pressure.
5.2.3.7
When the required dew point is reached, pressurize the system with nitrogen or sweet gas to the final lay-up pressure. Dry air may be used only if it has been preapproved. The system shall be maintained at a positive pressure of at least 30 psig unless this exceeds the design pressure of the system. Pressures up to the normal operating pressure have been used for lay-up for some systems. The dew point at the final lay-up pressure must be lower than -1°C.
5.2.3.8
Shut in the system, maintain and monitor the pressure per 5.2.2.4 during the lay-up period.
5.2.3.9
For pipelines, re-measure the dew point at all original test locations one week after reaching final lay-up pressure. If any dew point reading is found to be higher than -1ºC at the lay-up pressure, then the entire line must be dried again or an alternative preservation method must be implemented.

RE: TYPE OF LAY-UP FOR STAINLESS STEEL PIPINGS

(OP)
Thank U Mr.C2it & 3LittleInch for your valid info,
Will take care while making further posts

RE: TYPE OF LAY-UP FOR STAINLESS STEEL PIPINGS

(OP)

Thank U Mr.bimr,
Actually this for an Aramco Project, the service is for cooling water. This is a pipe replacement project, the previously installed pipes been badly affected with MIC. I have gone through the SAES A-007 already, the problem here is the pipes are loop formed and hence there is no option left for using a scrapper or mop. we are planning to hydrotest the loop with out any valves or strainers, and purge the line with hot air once the water been drained completely. After the re installation of the valves and associated components the line will be continuously purged with nitrogen and hold to a pressure around 30 PSI hence checking the dew point temperature.
We are not sure about the result, can u suggest me anything on this.

RE: TYPE OF LAY-UP FOR STAINLESS STEEL PIPINGS

You might consider adding a biocide to the hydrotest water or using dehumidified air.

RE: TYPE OF LAY-UP FOR STAINLESS STEEL PIPINGS

(OP)
Thank U Mr.bimr,
Thank You for your kind advise

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