Piping and Equipment Cleaning Specification

This content provides you with a example piping and equipment cleaning specification. This article is useful for field inspectors.

1.       GENERAL – Piping and Equipment Cleaning Specification

1.1. This specification covers general requirements for cleaning of piping and equipment in construction and commissioning works for the plant. All required equipment, devices, tools, materials and labors for any construction or commissioning work shall be provided by Construction Contractor. 

1.2.    UNITS – Piping and Equipment Cleaning Specification

Unless otherwise specified, Metric, Celsius and Kilogram unit shall be applied as the measurement system for the drawings and documents to be submitted, except that nominal size and rating of piping components may be inch (B) and pound (LB) system. 

1.3.    RELATED CONSTRUCTION SPECIFICATIONS – Piping and Equipment Cleaning Specification

The related construction specifications to supplement this specification are as follows:

Pressure test of Piping System  

1.4.       SPECIFIC JOB REQUIREMENTS

Specific job requirements such as Owner’s special and/or local requirements as well as specific job data are in contradiction to this specification, specific job requirements shall govern.

All instruction in preliminary and final operation manual, licensor’s or vendor’s requirements shall be considered and applied by Construction Contractor. 

1.5.   SAFETY AND SANITATION – Piping and Equipment Cleaning Specification

1.5.1.   Observance of laws and regulations, prevention of accident Construction Contractor shall observe the applicable laws and regulations for safety and sanitation concerning the following items, during the works and be fully responsible as the enterprise.

A.    Laborer’s safety and sanitation

B.    Prevention of environmental pollution

C.    Handling of dangerous substances

1.5.2.      Personnel in Charge for Safety and Sanitation

Construction Contractor shall assign the person in charge of safety and sanitation at site and let him manage the safety and sanitation affairs.

1.5.3.      Observance of Rules

Construction Contractor shall obey the safety and sanitation rules prescribed by Consultant.

1.5.4.      Measures for Safety

Construction Contractor shall take utmost care not to give any damage to the plant personnel and equipment including third person during the works.  Necessary additional measures for safety shall be taken, when Consultant requires to do so.

1.5.5.      Governmental Procedures

Governmental procedure concerning the safety and sanitation should be taken by Construction Contractor when it is his duty. In this case, these procedures shall be taken after getting Consultant’s personnel approval.

1.5.6.      Participation in Council for Safety and Sanitation

Construction Contractor shall participate in the council for safety and sanitation which will be established at the site and cooperate in prevention of accident. 

2.    CODES AND STANDARDS – Piping and Equipment Cleaning Specification

2.1.    The applicable codes and standards shall be as per ASME B31.3 (Latest Edition) Process Piping.

2.2.  It shall be the responsibility of Construction Contractor that the works conform to the specified codes and standards or legal requirements.

2.3.   Where there are conflicts between drawings and specifications and the specified codes and standards or legal requirements, such conflicts shall be immediately referred to Consultant. 

3.    GENERAL REQUIREMENTS – Piping and Equipment Cleaning Specification

3.1.    TREATMENT FOR PIPING COMPONENTS

Vinyl caps which cover end of piping component such as pipe and valves shall not be removed till the fabrication. 

3.2.   CLEANING OF FABRICATED PIPING – Piping and Equipment Cleaning Specification

Inside surface and welding surface of fabricated piping shall be free from slag, chambers, scales and other foreign matter with grinder, chisel, wire brush, etc., and be air blower. After completion of air blowing and checking, ends of the piping shall be covered with vinyl or veneer cap, etc. till the installation in the field.

4.      PROCEDURE OF CLEANING – Piping and Equipment Cleaning Specification

4.1.   GENERAL

4.1.1.   Cleaning method shall be selected in the following method considering kind of fluid, pipe material and condition of internal surface of piping to be cleaned. Cleaning method and extent to be applied shall be as specified in Specific Job Requirements. (See Table 1)

A. Water cleaning shall be applied in case that the fluid of piping is liquid. But, in case that water cleaning is not adequate, other suitable flushing method shall be applied.

 B. Air cleaning shall be applied in case that fluid of piping is gas. But in case that air cleaning is not adequate, other suitable cleaning method shall be applied.

C. Chemical cleaning shall be applied to field installed Lube Oil line, compressors suction lines, plate type heat exchanger inlet line, steam generation loops, piping around adsorber tower and all other parts that specify in operation or vendor’s manual unless otherwise specified by the Owner.

D. Oil cleaning shall be applied to field installed Lube Oil line after chemical cleaning, unless otherwise specified by the Owner.

E.  Mechanical cleaning –

F. Steam cleaning shall be applied in case that the fluid of piping is steam and for other equipment that specify in operation manual. But, in case that steam flushing is not adequate, other suitable flushing method shall be applied.

G.   Others

4.1.2.  Temporary strainers shall be used as follows:

A. After installation of piping, the temporary strainers with 80 mesh x #38 screen shall be installed and cleaning performed until no foreign material comes to the strainer.

B. The temporary strainers shall be installed at pump suction piping, piping upstream of control valve and other location specified in Specific Job Requirements.

C.    Mark plate shall be attached to the temporary strainers to distinguish from other strainers.

D.      After a constant period of initial operation, all temporary strainers shall be removed. 

4.2.     WATER CLEANING – Piping and Equipment Cleaning Specification

4.2.1.    As a rule, pure water, service water, steam condensate industrial water, etc. shall be applied with maximum chloride ion content 50ppm and sea water shall not be applied. If using of sea water is unavoidable, washing by fresh water shall be carried out at least on time to prevent corrosion after using of sea water.  In any case, sea water shall not be used for cleaning of austenitic, stainless steel.

4.2.2.    Water cleaning shall be performed by the method of running be pressurized water and hammering, or rapid draining with water filled.  Hammering shall, however, not be performed for austenic stainless steel pipe, copper pipe, aluminum pipe.

4.2.3.    After cleaning, drying by compressed air or natural drying shall be carried out. Drying by superheated steam shall be carried out with agreement between Owner and Consultant.

4.2.4.    Number of times of cleaning shall be as follows:

A.  Primary cleaning – two times or more

B.  Secondary cleaning – one tim

4.2.5 The primary cleaning shall be performed for each assemble piping. And secondary cleaning, as a rule, shall be performed for whole of the piping system including the equipment.

4.2.6.    Where instruments are included in piping system to be cleaned the instruments shall, as a rule, be disconnected and spool pipe (distance piece) shall be inserted instead.

4.2.7.    When cleaning is carried out in condition where control valve is connected, the procedure shall be as follows:

A.  Disconnect companion flanges in upstream side of the control valve and cover openings of the control valve.

B.  Clean the piping of upstream side.

C.  Connect the control valve and piping of upstream side after completion of cleaning.

E. Close the control valve, open by-pass valve, and then clean the piping of downstream side. Where the by-pass valve is not installed, the temporary strainer having austenitic stainless steel screen of No. 50 specified in ASTM E11 shall be inserted.

4.2.8.    All accessories such as circulation pump, temporary pipes, spools, hoses, strainer, tank, etc. shall be supplied by Construction Contractor.

 4.3.            AIR CLEANING – Piping and Equipment Cleaning Specification

4.3.1.    Air cleaning shall be performed by the method of blowing be pressurized air and hammering.  Hammering shall, however, not be performed for austenitic stainless steel pipe, copper pipe and aluminum pipe.

4.3.2.   Number of times of the cleaning shall be as follows:

A.    Primary cleaning – two times or more

B.    Secondary cleaning – one time or more

4.3.3.    The primary cleaning shall be performed for each assembly piping. The secondary cleaning shall, as a rule, be performed for piping from equipment to adjacent equipment. Whether of not the equipment is included, the cleaning method shall be determined considering shape, internal construction and packing of the equipment and according to overall cleaning plan.

4.3.4.  Treatment of instruments and handling of temporary strainer shall conform to the requirements specified in Para. 4.1.2. 

4.4.            CHEMICAL CLEANING – Piping and Equipment Cleaning Specification

4.4.1.    Chemical cleaning shall be applied to field installed lube oil line and compressor suction lines, plate type heat exchanger inlet line, steam generation loops, piping around adsorber towers and all other parts that specify in operation or vendor’s manual.

4.4.2.    Construction Contractor is responsible to provide specific procedures for each chemical cleaning. These procedures shall include marked up drawings, volume of system, required chemical materials, neutralization procedure and all other requirements.

The application of chemical materials shall be in accordance with supplier’s instruction.

As a rule, chemical cleaning by circulation or pickling shall be applied and the general procedure shall be as follows:

1)      System isolation and flushing with water.

2)      Degreasing before chemical application.

3)      Sufficient rinsing.

4)      Acid cleaning

5)      Sufficient rinsing

6)      Passivation

7)      Preservation up to start up

8)      Any procedure or method for chemical cleaning shall be subject to the Owner’s approval and the performance of such chemical cleaning shall be to the Owner’s satisfaction.

4.4.3.     Where oil cleaning specified in Para. 4.5 is applied, the inside of piping shall be given a coat of anti-corrosive oil except when oil cleaning is to be carried out successively after completion of the chemical cleaning.

4.4.4.     Detail procedure and check list for chemical cleaning is shown in attachment #1 and #2. Licensor or vendor’s instructions shall be considered by Construction Contractor. 

4.5.            OIL CLEANING

4.5.1.    Oil cleaning shall be applied to the field installed lube oil piping system after the chemical cleaning specified in Para. 4.4 has been performed. Vendor’s instruction shall be considered by Construction Contractor.

4.5.2.   The procedure shall be as follows:

A. The cleaning shall be performed by the method of circulation of the oil and hammering.  Hammering shall, however, not be performed for copper pipe.

B. Oil to be used shall have the good quality, and be suitable for the machinery, and shall be completely replaced with the specified oil after cleaning.

C. After completion of cleaning, piping system shall be checked that no foreign matters are present in temporary strainer having two screens of No. 200 specified in ASTM E-11 for oil piping of centrifugal compressor, and in temporary strainer having a screen of No.100 specified in ASTM E-11 for other oil piping. 

4.6.            STEAM CLEANING – Piping and Equipment Cleaning Specification

4.6.1.  Steam cleaning shall be performed after completion of pressure test. Pipe support shall be attached to exhaust piping to prevent accident caused by the reaction force. In general, following items are required during the cleaning.

A.  Removal or opening of steam trap, vent and drain

B.  Warming up for piping (To be blown gradually with cooperation by operator)

C.  Checking for expansion joints, spring hangers, etc. caused by thermal expansion.

D.  Steam cleaning temperature (Cleaning shall be performed at the temperature near to the operating temperature considering operating condition of boiler.)

E.  Cooling down (To remove the scale effectively by temperature change, it is required to perform cleaning and cooling cyclically, having temperature difference as large as possible between cleaning and cooling period.)

4.6.2.   Judgment on result of steam cleaning shall be generally be done by checking of the target inserted in line opening or foreign material present in the drain sampled if applicable. Strict requirements of steam driven machinery suppliers shall be considered. 

4.7.            MECHANICAL CLEANING – Piping and Equipment Cleaning Specification

4.7.1.    Mechanical driven rotary cleaning tool or wire brush shall be applied and pushed through the inside of the pipe.

4.7.2.      Shot or sand blasting, if required, shall be performed. 

4.8.            OTHER CLEANING METHODS – Piping and Equipment Cleaning Specification

4.8.1.  Cleaning by the use of pig shall conform to specific job requirements.

4.8.2.   Cleaning by sodium hydroxide solution shall conform to specific job requirements.

4.8.3.     Special cleaning, if specified for special piping components of systems, shall conform to specific job requirements.

4.8.4.     Some piping cannot be cleaned by any method due to the special configuration such as too big bore piping (non flushing line).

Non flushing lines shall be identified at the initial stage of piping works, and will be manually cleaned before installation with witness of Owner.

DETAIL PROCEDURE FOR CHEMICAL CLEANING 

1  General Requirements for Chemical Cleaning – Piping and Equipment Cleaning Specification

1.1 The layout of the circulation system shall assure complete circulation and that there are no dead ends or branches that will create traps.

1.2 Each circulation system must have adequate high point vents and low points drains.

1.3 The piping to be chemically cleaned must be sufficiently flushed and degreased prior to chemically cleaning operation.

1.4  The piping shall be pre-inspected to assure that no foreign material is present which cannot be removed by chemical cleaning. 

2    Chemical Cleaning – Piping and Equipment Cleaning Specification

2.1 The circulation loop shall be established and the system shall be filled with water or the rinsing water used at degreasing operation.

2.2  The water shall be circulated and water temperature shall be raised to required temperature.

2.3  When the temperature is achieved, chemicals shall be injected:

2.4  The solution shall be circulated until the iron content in the solution levels out constant, but in any event a circulation period of 8 hours is recommended.

2.5 During the circulation period, the complete filling of the piping with solution shall be checked. Any gas volumes accumulated at high points shall be safely vented. 

2.6 After the circulation period, the system shall be drained and flushed to tankers by displacing the inhibited acid with rinse water until the pH value of the outflow is equal to that of the inflow and no appreciable amounts of debris appear at the drain points. 

3  Passivation – Piping and Equipment Cleaning Specification

3.1 After pH value is adjusted, circulation shall be re-established and water temperature shall be raised to required temperature.

3.2 When the temperature is achieved, the water in the system shall be treated as follows:

1) Inject 0.5% w/w citric acid and circulate for 30 minutes.

2) After this time, Inject ammonia to a pH of 9.5.

3) When solution is homogeneous, Inject 1% sodium nitrite.

4) Circulate the solution for a minimum 4 hours, then drain the system and rinse briefly with ammoniated water.

3.3 After this treatment, the system shall be throughly drained and blown through with nitrogen.

3.4  No water shall remain in the cleaned piping. 

4    Preservation – Piping and Equipment Cleaning Specification

4.1 The chemically cleaned piping surface shall be properly protected until commissioning of piping.

4.2 Pipe spools cleaned in a batch operation shall be sprayed with a light preservation oil and all openings shall be sealed to avoid ingressing of foreign material.

4.3  Compressor suction piping and process piping shall be blanketed with nitrogen. 

5    Inspection and Testing of Chemical Cleaning

5.1 All parts shall be visually examined prior to commencing chemical cleaning operations to determine the adequacy of pre-cleaning and to determine the presence of mill varnish.

5.2 The log for each cleaning operation shall be kept to identify the piping included in the individual circulation loop.

5.3 The log shall state the chemicals and concentrations used, duration of each individual cleaning step, temperatures, name of inspectors, time, etc.

5.4 Temperature must be closely monitored, especially the temperature of the degreasing solution cannot exceed 80°C.

5.5 The concentrations and the efficiencies of the solutions shall be controlled by chemical analysis. As a minimum following test shall be performed.

1) sulphuric acid strength

2) iron level in solution

3) inhibitor efficiency

4) citric acid strength (until ammonia is added)

5) pH value of solution

6) Conductivity

7) Alkalinity

8) Clearness