Oxygen cleaning services can be defined as specialized cleaning for components, equipment, piping, and systems used in the production, storage, distribution and use of gaseous oxygen (GOX) and liquid oxygen (LOX). LOX is the liquid form of elemental oxygen (O2). Examples of industries that use LOX systems include Aerospace, Military and Defense (NASA), and the compressed gas industry.
Oxygen cleaning services are necessary for both safety and product purity considerations. Oxygen cleaning reduces contaminants that can lead to a fire or potential explosion. It also reduces the chance of autoignition at a temperature much lower than expected by material selection. Combustion in systems that contain enriched oxygen requires only fuel and an ignition source because the gaseous or liquid oxygen is the oxidizer.
Types of Contaminants Removed in Oxygen Cleaning
The primary goal of precision cleaning for oxygen service is the removal of any material, chemical, residue, contaminant, or particulate matter that could promote combustion or impact product purity.
Contaminants can be classified into three categories, per ASTM G93.
1. Organic Compounds
- Volatile organic compounds (VOC)
- Grease and oils (Hydrocarbon based)
2. Inorganic Compounds
- Water-based detergents and cutting oils
- Mineral acids and solvents
- Weld slag and metal grindings or filings from fabrication
- Particles, lint, and fibers
Oxygen equipment and systems, including all components and parts, must be appropriately cleaned to remove harmful contamination prior to the introduction of oxygen. An example of this is hydrocarbon-based residue. These are often made up of small amounts of oils and greases, which are commonly used in manufacturing environments and end up on the surfaces of newly-produced hardware.
When a hydrocarbon-based residue comes into contact with an enriched oxygen atmosphere or a strong oxidizer, the temperature at which it will ignite and burn is lowered – sometimes low enough that it will catch fire at or below room temperature. If a fire ignites, the presence of many oxygen molecules in the immediate area causes it to burn hotter and faster than usual, so much so that it may even cause an explosion.
The other contaminant of concern is particulate matter. These can travel in a stream of moving gas within a pipe or tube. In an oxygen-enriched atmosphere, especially one under high pressure, things that normally are not considered flammable may catch fire and burn. The only requirement is a spark. If particles are travelling with the gas stream and they strike the wall of the pipe or tube with enough velocity, a small hot spot may develop.
Moreover, if the particle is metallic, a spark might even occur. In either case, contaminants in the pipe, or even the wall of the pipe itself, may catch fire. This can result in a pipe rupture, releasing high-pressure gas and thereby endangering everything in the area. High-pressure gas ruptures are essentially explosions and it is not uncommon for shrapnel to be propelled for some distance.
For oxygen-enriched environments constructed using certain alloys (i.e. stainless steel), require not only combustible organic and particulate contamination removal but also an optimal passive surface which provides corrosion resistance. A passive layer surface will inhibit oxidation and corrosive reactions, thus minimizing particulate contamination.
Astro Pak uses only approved chemistries and cleaning processes to provide certification to meet multiple ozone and oxygen piping system specifications, including aerospace launch facility LOX and gas system cleaning and verification. Technical cleanliness verification with analytical methods is an integral part of Astro Pak’s oxygen cleaning service protocols.
Astro Pak oxygen cleaning services adhere to internationally recognized published standards such as CGA G-4.1, Cleaning of Equipment for Oxygen Service. This standard describes the cleaning methods and requirements for equipment used in the production, storage, distribution, and use of liquid and gaseous oxygen to reduce the risk of fire, explosion, or promotion of combustion. Cleaning in accordance with this publication is required for all surfaces in contact with a gas or liquid that has an oxygen concentration greater than 23.5%.
Note: Data for assessing the compatibility of non-metallics (i.e., organics) with gaseous oxygen (GOX) and liquid oxygen (LOX) can be found in the ASTM G63 Standard, Guide for Evaluating Nonmetallic Materials for Oxygen Service.
Did you know? Astro Pak Downey cleanroom was featured in the CGA Handbook for cleaning components, equipment, and systems for oxygen service
Where are the Oxygen Cleaning Services performed?
Precision oxygen cleaning services can be performed on-site at client facilities and at Astro Pak shop locations, or an Astro Pak cleanroom facility.
On-Site or Shop Oxygen Cleaning Services
Oxygen cleaning services can be performed on-site at client facilities for pre-operational or operational systems, in any of the following designated system types, and at any stage in the development of the system:
- Pre-commissioning of new construction
- Maintenance and shut-downs
Cleaning a component or a system for oxygen service involves the removal of combustible contaminants including surface residue from manufacturing and processing (M&P), hot work, and assembly operations. It also includes the prevention of recontamination before or during final assembly, installation, and use.
Oxygen cleaning services for component parts of systems including hoses, tubing, piping, and other equipment are available on-site at the client’s facility. Alternatively, these cleaning services are also available for components and equipment at one of Astro Pak’s nationwide shop locations.
Learn more about our Cleanroom Oxygen Cleaning services
Trust the Experts
With over 60 years of experience in the industry, Astro Pak offers quality cleaning services to meet the requirements for hundreds of industry specifications, including those of aerospace contractors, ULA, NASA, the Department of Defense, and many private organizations. Our scientists and experts provide guidance, support and consultation on precision cleaning to some of the world’s most prestigious institutions. These include JPL, Lawrence Livermore National Laboratory, MIT, Cal-Tech and others. We have experience with large high-pressure gaseous oxygen as well as liquid oxygen tanks, lines, tubing and valves. Additionally, we have worked on many ozone systems, both large and small. Our facilities are large, modern, and staffed with highly-trained employees dedicated to meeting and exceeding our customers’ expectations. Our Research & Development professionals can develop a customized oxygen cleaning process that meets nearly any requirement in an efficient and cost-effective manner.
When our job is complete, you will receive QMS/cGMP compliant documentation packages for your system and equipment maintenance records.
Let our experienced and credentialed team of chemists, engineers, and other professionals on staff exceed your expectations.
Frequently Asked Questions
Oxygen Cleaning, also referred to as Oxygen Service Cleaning, is cleaning parts that will be used in an oxygen or oxidizer environment. To accomplish this, parts are not cleaned using oxygen; rather, the parts are degreased using solvents and/or alkaline detergents in an aqueous solution to remove the contaminants and residue that are not compatible with an oxygen system. This cleaning process is important to ensure that substances which are incompatible with oxygen or other oxidizers are removed from the part. Failure to do so may result in system failure, product failure, and/or combustion.
There is a wide range of cleanliness criteria for oxygen service depending on the use of the system. The less critical conditions include breathing air, non-oxygen gases; and the more critical conditions include liquid oxygen, high pressure gaseous oxygen, spacecraft systems, etc.
For each environment there is a set cleanliness criteria established. Usually the standard is noted in a cleaning specification, and the cleanliness verification target ranges from 47 mg/sq foot of non-volatile residue (NVR) for the least critical conditions, to 1 mg/sq foot of NVR and below for the more critical systems. Cleanliness criteria can be less than 1 mg/sq foot for oxygen systems, but typically 1 mg/sq foot of NVR represents the more common lower limit range of the requirement.
After a part has been cleaned and verified, it is important to package the part correctly in order to maintain the cleanliness level until use or assembly into the final hardware, equipment, or system. For high pressure and liquid systems, cleanliness criteria usually also includes particle count limits. The allowable particles are typically in the range of level 100 – 300 (measured in micrometers), as noted in such specifications as IEST 1246.
- LOX and GOX Piping & Hoses
- Process & Storage Tanks
- Product & Distribution Piping
- Spools, Coils & Nozzles
- Heat Exchangers
- Vessels &Tanks
- Clean in Place (CIP)
- Tubing, Hoses
- Valves and Gauges
- Components & Hardware
- ASTM G-93 (Standard Practice)
- ASTM F-311, F-312, F-331 (Testing Standards)
- CGA G-4.1 (Compressed Gas Association)
- MSFC Spec 164
- PraxAir GS-38
- NFPA 99C
- ANSI B 40
- IEST-STD-CC-1246 revisions D & E
- Many Individual Private Industry & Government Specifications
- Aerospace, Military & Defense
- Medical Device
- Heath Care
- Power Generation
- Food & Beverage
- Mining & Metals
- Household & Personal Care
- Chemical Manufacturing & Distribution