1. PURPOSE
1.1 This procedure defines acceptable cleaning agents and cleaning methods for equipment in oxygen service and to ensure that all methods and cleaning agents used for oxygen cleaning are approved for use.
2. SCOPE
2.1 This procedure applies to all engineering, operations, and construction activities associated with oxygen cleaning of equipment manufactured or used by Air Products worldwide.
3. DEFINITIONS
3.1 None
4. SUMMARY
4.1 The objective is the minimization of all the safety, health and environmental risks associated with cleaning equipment for oxygen service.
4.2 Prior to be being placed into oxygen service for the first time oxygen containing systems or equipment with oxygen shall have been cleaned and inspected to meet the acceptance criteria.
4.3 Only methods and solvents approved by means of this procedure shall be used for cleaning of oxygen systems. Whenever practical, aqueous (water based) cleaning agents should be utilized as they offer environmental, health and safety advantages.
4.4 Air Products facilities and operations that are involved with cleaning for oxygen service shall not use 1,1,1-trichloroethane (TCA) or any other significant ozone-depleting chemical as a degreasing or cleaning agent. Likewise trichloroethylene, a known carcinogen, shall not be used.
4.5 Written procedures that have been developed through workplace risk assessment and job safety analysis shall be used for oxygen cleaning. Only persons who have been specifically trained for cleaning equipment and systems for oxygen service shall carry out cleaning or inspection of systems for oxygen cleanliness.
4.6 Only approved suppliers shall be used for supply of services or equipment involving oxygen cleaning.
4.7 When feasible, all parts and equipment shall be cleaned for oxygen service by the manufacturer or supplier prior to installation. Procedures that will ensure the maintenance of cleanliness until final assembly must be implemented.
4.8 Prior to be being placed into oxygen service following maintenance, all equipment and pressure systems in contact with oxygen shall have been cleaned and inspected to meet the acceptance criteria (see 6.3).
4.9 Equipment and systems that have been cleaned for oxygen service shall be sealed by suitable means and identified as Cleaned for Oxygen Service and a certificate provided.
5. PROCEDURE
5.1 Approved Methods for Oxygen Cleaning Approved methods for cleaning for oxygen service are given in Appendix A. Guidance is also given in reference documents from ASTM, CGA, and EIGA. Appropriate written procedures must be developed for each cleaning method and/or agent to ensure safety, health, and environmental aspects as well as the required cleaning level. Procedures and periodic training are being relied upon to achieve the cleanliness. Managers are responsible for establishing training, certification programs, and developing safe and environmentally sound work practices in accordance with Risk Assessment and JSA procedures. Approved cleaning agents are given in Appendix B.
5.1.1 The use of Low Vapor Pressure (LVP), slow-evaporating, hydrocarbon-based cleaning agents (for example, terpenes) shall be strongly discouraged because of the risk of a hydrocarbon residue remaining in the system and subsequently contacting oxygen. LVP solvents require special training and procedures to mitigate this risk. In addition, LVP cleaning agents are usually flammable and/or combustible.
5.1.2 The use of High Vapor Pressure (HVP), fast-evaporating, hydrocarbon-based cleaning agents, which are also flammable, shall be minimized. They shall be used only for applications when other cleaning agents or methods are not practical. The use of flammable HVP cleaning agents always requires extreme care, special training, and written procedures. Flammable HVP cleaning agents shall not be sprayed.
5.2 Isopropyl Alcohol
5.2.1 Isopropyl alcohol (also known as IPA and isopropanol) is between a LVP and a HVP solvent. With certain exceptions IPA has not been approved (Appendix B) because it is a poor solvent to remove organics, is flammable, has a high boiling point and has a high heat of vaporization. The latter two properties greatly impede its evaporation. IPA is often contaminated with water, which further impedes its evaporation. IPA is ineffective for soaking to remove organics.
5.2.1.1 The non approval of IPA as a solvent has some limited exceptions. IPA is approved for: Spot light duty cleaning with Rocol spray. Spot light duty cleaning (fingerprints, lint, etc.) by wiping with a clean rag dipped in IPA.
5.2.1.2 In the following circumstances IPA may be used following a risk assessment and JSA approved by the appropriate EHS representative. At sites where the property owner has a written policy prohibiting the use of chlorinated solvents but approving the use of IPA. In such cases AP policy and procedures shall be explained in writing to the property owner.
5.2.1.3 The above exceptions do not include soak cleaning with IPA.
5.2.1.4 When used, ample time and/or purge flow is required for complete evaporation of the IPA.
5.2.1.5 Isopropyl alcohol is approved for use as a lubricant for assembling blocks of packing in ASU columns. This approval is based upon the fact that small amounts are used and that very ample time is available for the IPA to evaporate before the oxygen would be placed in the column.
5.3 Methylene Chloride in Open and Closed Systems
5.3.1 Methylene chloride (also known as dichloromethane) is an inexpensive and excellent HVP solvent. Further, it has a very low ozone depleting potential. To prevent potential adverse health effects, a full JSA/risk assessment must be conducted for each activity requiring the use of methylene chloride to establish the necessary control and handling measures.
5.3.2 US Only – Methylene chloride is regulated as a potential carcinogen by the Occupational Safety and Health Administration (OSHA), therefore its use is discouraged in the United States. If methylene chloride must be used for a particular application, contact Air Products Industrial Hygiene for compliance guidance.
5.3.3 For health reasons as well as for soil and water environmental concerns, methylene chloride shall be used in closed (recovery) systems. Escaping vapors must be vented to a safe location away from personnel and comply with relevant environmental legislation.
5.3.4 Methylene chloride may only be used in open systems if the specific application is approved by the OSC, Air Products Industrial Hygiene (US/Asia), and/ or the Field Safety Group (Europe).
5.3.5 Methylene chloride may be used as a cleaning agent for complex plant washouts in accordance with Gases Operations Procedure 34-110919. Contact Air Products Industrial Hygiene or the Field Safety Group (Europe) for guidance.
5.6 Approval Process for New Solvents
5.6.1 The approval process for a new solvent is summarized in Appendix C.
5.6.2 The initial inquiry should be made through EH&S Process Safety Group (US) or the European EH&S Group. Initial information should include: Application and method. Is it a new technique/product for an existing application? Does it have advantages over existing technique/product? Available vendor technical data.
5.6.3 The item will be presented for discussion at the appropriate Approval Committee with a request for a decision to be made on the Solvent Approval. It is envisaged that this type of presentation would be on an ‘as needed’ basis. Feedback would be directed back to those persons who made the initial inquiries as well as to the relevant experts, including liaison with the Oxidizer Safety Committee (OSC).
5.6.4 Proper alternative cleaning methods or agents shall be selected based on contamination being removed, material being cleaned, and local conditions. Local conditions include the following: Environmental regulations (all levels of government). Availability of utilities (for example, electrical power, hot water). Ambient temperatures and availability of a heated enclosure to aid drying. Availability of cleaning agents. Shipping of cleaning agents. Competence/Training of individuals. Safe and environmentally sound disposal of spent cleaning agents and wipers.
5.6.5 If a new solvent for oxygen cleaning is approved as a result of a decision from the Approval Committee then the listing from Appendix A will be updated.
5.6.6 The new method or solvent shall be subject to a risk assessment/job safety analysis and written procedures and training developed prior to final approval and implementation.
5.7 Oxygen Cleaning by Suppliers and Contractors
5.7.1 Suppliers of equipment that requires cleaning for oxygen service shall be informed of the methods and agents defined by this standard to understand the minimum requirements for cleaning.
5.7.2 The responsibility for attaining the levels of cleanliness specified in the oxygen acceptance criteria rests with the supplier.
5.7.3 All contractors performing oxygen cleaning shall, under the supervision of Air Products, have an equivalent level of competence to Air Products employees for the same task.
5.8 Acceptance Criteria
5.8.1 Acceptance criteria are given in 3PI70001 Cleaning Levels and Acceptance Criteria for Air Separation Plant Piping and Equipment or AO3 Oxygen Clean (Class AA) Inspection and Acceptance Requirements.
5.9 Waste Disposal
5.9.1 Spent cleaning agents and any associated cleaning materials (for example, cloths and wipers) might need to be categorized as hazardous wastes and disposed of properly. The appropriate national or regional environmental coordinator shall be consulted for proper disposal guidance.
5.9.2 For guidance on the correct disposal of cleaning agents refer to 25-011202, Waste Management.
5.10 Health Assessment
5.10.1 When using cleaning agents, handling precautions specified by the supplier and Material Safety Data Sheet (MSDS) shall be used as part of the risk assessment to determine the correct controls (in Europe refer to 25-011313AN). The risk assessment shall be used to define the requirements for health surveillance (see Health Screening and Surveillance procedure).
6. RELATED INFORMATION
6.1 EH&S Documents
Job Safety Analysis (JSA)/Workplace Risk Assessment
25-011202 Waste Management
25 011206 Ozone Depleting Substances
25-011209 AM Environmental Risk Assessment
25-011212 AN Environmental Aspects and Risk Assessment
25-011313 AN Chemical Agents Risk Assessment
25-011314 AM Hazard Communication
6.2 Air Products Operations Documents 34-110919 Plant Washout (cleaning agent or solvent)
6.3 Air Products Engineering Documents
3PI70001 Cleaning Levels and Acceptance Criteria for Air Separation Plant Piping and Equipment
4WPI-SW70003 Oxygen Clean (Class AA) Inspection and Acceptance Requirements
6.4 European Industrial Gases Association (EIGA) EIGA Document 33 Cleaning Equipment for Oxygen Service
6.5 American Society for Testing and Materials (ASTM)
ASTM G93-96 Standard Practice for Cleaning Methods and Cleanliness Levels for Material and Equipment Used in Oxygen Enriched Environments
6.6 Compressed Gas Association, Inc. (CGA) CGA Pamphlet G-4.1 Cleaning Equipment for Oxygen Service
Appendix A Table 1 Cleaning Procedures for Oxygen Service Based on Application
| Category | Field Application | Recommended Cleaning |
| A | Construction sites within which Air Separation Unit (ASU) equipment is being fabricated and/or installed. | For carbon steel with rust or scale, sandblasting to a white metal surface is the method of choice. For other materials, hot water/steam (aqueous) detergent cleaning is preferred. Rinsing of residual aqueous cleaning agents is especially important, as the detergent residues are not oxygen compatible. Availability of utilities/water, electric power, and heated enclosures are important. Due to the need to prevent unauthorized use, other cleaning methods/agents that require special precautions and training (for example, ensuring removal from equipment, limited personal exposure, flammability) are generally not suitable for use at these sites. |
| B | Stationary plant equipment, including piping, vessels, and cylinders. Generally involves large scale components and must be done on-site. | Hot water/steam detergent cleaning is preferred. Availability of utilities/water, electric power, and heated enclosures are important. Flammable (HVP) solvents may be used in small quantities. |
| C | Field installations, including customer stations piping and components. Generally, cleaning is done on a small scale in an open area. | HVP solvents in small quantities are acceptable because of a lack of a practical alternative. Utilities are not available, see section 5.3. |
| D | Large equipment fabrication facilities, including cryomachinery and vessel/column manufacturing. | Hot water/steam detergent cleaning is appropriate for large parts. Submersion in agitated baths (for example, ultrasonic) enhances cleaning. Caustic and acid-based cleaning might be appropriate provided that corrosion issues are adequately addressed. HVP solvents may be used in small amounts. |
| E | Small equipment fabricators, including instrument shops and laboratory scale equipment. | HVP solvents are preferred, see section 5.3. |
| F | Small equipment fabricators, including instrument shops and laboratory scale equipment. | Fixed detergent systems such as ‘washing machines’ or HVP solvents are preferred. |
| G | Oil removal from contaminated ASU equipment (plant washout). | Less complex systems such as brazed matrix Al or SS exchangers, liquefiers, main exchangers may be suitable for aqueous washing. Methylene chloride in a closed (recovery) system is preferred for difficult zones such as columns where dryout is a problem, see section 5.3. |
Appendix B Table 1 Cleaning Agents Approved for Oxygen Service
| Material | Application |
| TICKET | Small components in workshop conditions |
| Methylene chloride | Small scale cleaning of Tubes/Fittings/Equipment |
| Methylene Chloride | Complex Plant washouts |
| ISOPROPANOL (Rocol Industrial cleaner rapid drying Spray) | See paragraphs 5.2 through 5.2.1.5. Spot cleaning of accessible surfaces. |
| TDE (transdichloroethylene)
(Vertrel, Contact cleaner G3, 3M’s HFE-71DE) |
Small scale cleaning of Tubes, fittings, equipment. |
| 1.1 Dichloro-1-Fluoroethane (H141b)
(Genesolv 2004) |
Spray cans only. Small components and tubing. |
| 2-(2-butoxyethoxy) ethanol)
(Blue Gold (A), Simple Green (A)) |
All applications where detergent methods are acceptable |
| Beyond 2001 (A) | |
| Safezone solvent flux remover | Spray cans only. Small components and tubing. |
| Safezone precision cleaning solvent | Spray cans only. Small components and tubing. |
| Tramos | Small scale cleaning of Tubes, fittings, equipment. |
| Pyrene 1027 (A) [Oakite Products, Inc] | Small scale cleaning of Tubes |
| Clear Clean (A) [Classic Chemicals, Inc] | Small scale cleaning of Tubes |
| eOx cleaner | Small scale cleaning of Tubes, fittings, equipment. |
Note: small scale’ is a judgment but refers for example to cleaning of a small number of tubes or equipment where larger fixed cleaning equipment is not practical to use, so for example emergency repairs or customer site maintenance.
Table 2 Cleaning Agents Not Approved for Oxygen Service
| Material | Application |
| P3 GLIN | Any (due to leaving residue) |
| AMBERCLEAN FE10 | Any (due to leaving residue) |
| ROCOL U/C 2000 | Any (due to flammability concerns) |
| MICRO | Any (due to ineffectiveness) |
| ISOPROPANOL (Rocol Industrial cleaner rapid drying Spray) | Any except for Spot cleaning of accessible surfaces. See paragraphs 5.2 through 5.2.1.5.
(due to flammability concerns) |
| SONOCLOR | Any (due to environmental and health effects) |
| n-propyl bromide (Ensolv, Swansolv, HFE 7100) | Any (due to environmental and health effects) |
Note: Cleaning Agents Not Approved for Oxygen Service Appendix B Table 2 lists only the cleaning agents methods that have been evaluated, by definition the only approved cleaning agents and methods are those listed in Appendix B Table 1.
Appendix C Oxygen Cleaning Solvent Selection Process
