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Scuba Cylinder and Valves Support Pages

Click here to book your IDEST High Pressure Cylinder Visual & Hydrostatic Inspection Training Course

Aluminium, Steel and zinc dipped steel scuba tanks spare parts and support
Good tanks, bad tanks and tanks that go 'bump' in the night!

exploded scuba tank bombexploded scuba tank bombexploded scuba tank bombexploded scuba tank bombexploded scuba tank bombexploded scuba tank bomb

big steel J-bottle goes bang - thankfully nobody killed. Click to open incident report 150kb pdf

'TRAINING TO SERVICE SCUBA TANKS

The skills and information necessary to safely inspect and test high pressure scuba tanks are learnt by attending the following ASSET approved courses.

Cylinder Testing Course - Level 1 (Practices and Procedures - VISUAL INSPECTION)

Cylinder Testing Course - Level 2 (Metallurgy, Inspection and Determination - HYDROSTATIC INSPECTION)

The best free handbook available for the guidance of personnel involved in the visual inspection of DOT 3AL3000 scuba cylinders  is the Visual Inspection Guide produced and made available free of charge by the Luxfer company. You may download it here (see below). Please check the Luxfer site from time-to-time for a more recent download. There is plenty of other hard to find useful info listed here

 Download Luxfer DOT-3AL3000 Visual Inspection Guide(English) .ZIP (1.88Mb)

United Kingdom HSE Guide to 'Safe Use of Scuba Tanks' (192Kb)

Download German language tank testing information "flaschen_und_Ventile" (12.2Mb)

Catalina Tank Valve Insertion Instructions .PDF (30Kb)

Thermo Valve Maintenance Instructions.pdf (1.08Mb)

Offshore compressed air cylinder explosion report .pdfion (143Kb)

SCUBA Cylinder Manufacturing Specifications
Located in the technicians password protected area
<click here to Enter>

 


Introduction to scuba tank testing regulations

1.    American DOT-3AL3000 Cylinders

In America, the standards for testing high pressure cylinders are developed by the CGA (Compressed Gas Association) in conjunction with DOT (Department of Transport). The relevant CGA copyrighted specifications are listed below and are available for download here (from the CGA web site).

Special Publication Note Dec 2007 - Gauging NPSM 3/4 threads. Clarification statement for ASSET members

Test stations applying for DOT approval must have their own individually licensed copies of the CGA documents needed to carry out the cylinder inspections the test station offers.

Note:- That the CGA charges fees for each downloaded document. A handful of documents may well cost you a few hundred US$

  • C-1      Methods for Hydrostatic Testing of Compressed Gas Cylinders
  • C-6      Carbon Dioxide
  • C-6.1   Standards for Visual Inspection of High Pressure Aluminum Compressed Gas Cylinders
  • G-4      Oxygen
  • G-4.1   Cleaning Equipment for Oxygen Service
  • G-4.3   Commodity Specification for Oxygen
  • G-6.2   Commodity Specification for Carbon Dioxide
  • G-6.3   Carbon Dioxide Cylinder Filling and Handling Procedures
  • G-7      Compressed Air for Human Respiration
  • G-7.1   American National Standard Commodity Specification for Air
  • G-8.2   Commodity Specification for Nitrous Oxide
  • P-1      Safe Handling of Compressed Gases in Cylinders
  • P-2      Characteristics and Safe Handling of Medical Gases
  • P-5      Suggestions for the Care of High Pressure Air Cylinders for Underwater Breathing
  • P-14    Accident Prevention in Oxygen Rich and Oxygen Deficient Atmospheres
  • P-2.5   Tran filling of High Pressure Gaseous Oxygen to be Used for Respiration
  • PS-7    CGA Position Statement of the Safe Transportation of Cylinders in Vehicles
  • SB-7    Rupture of Oxygen Cylinders in the Diving Industry

The necessity for compressed gas cylinders to be tested and approved when transported by road (in accordance with the CGA regulations) is enshrined with US law within the Code of Federal Regulations

  • CFR   Title 49 Parts 100 to 185
  • CFR   Title 21 Parts 200 to 299
The current approved USA DOT testers listing is given here http://hazmat.dot.gov/sp_app/approvals/hydro/hydro_retesters.htm

Special Notes for Fill Station operators DOT-3AL3000 Cylinders

  • No cylinder can be filled with altered markings. Condemned DOT Cylinders have the 'DOT' and the pressure ratings 'X'd out
  • Only cylinders with approved burst disks may be filled
  • Only aluminum cylinders marked '3AL' may be filled.
  • All the cylinders below must be removed from service

        SP890    ,    SP6688    ,    E6688    ,    SP6576    ,    SP7039    ,    E7235-4500psi

  • All cylinders marked below cannot be filled until they have been tested by a hydro facility, NDT tested, and over stamped with '3AL'. Also note:-
    • That these older cylinders are made of the troublesome T6351 aluminum alloy.
    • The alloyed used in these cylinders has well known susceptibility to Static Load Cracks (SLC)
    • They have caused several catastrophic explosions and the deaths of many cylinder fillers.
    • They are subject to 4 monthly visual inspection periods if in heavy use such as at a dive school

    SP6498    ,    E6498    ,    E7042    ,    E8364    ,    E8422

    An example of a 'dodgy' cylinder thus marked is DOT-E6498-3000. This marking should make you instinctively reach for your NDT tester if it ever graces your test bench.

    Read this US DOT report for further information http://hazmat.dot.gov/regs/notices/sa/not94_7.htm

     

2.    European Cylinders

EC legislation has given rise to the Carriage of Dangerous Goods acts CDGCPL-2 requiring all transportable pressure vessels be subject to periodic inspection by an approved person. Though in many of the countries that make up the E.C., testing to older legislation (such as the old British Standard system in the United Kingdom) still continue to be applied until replaced by unified European wide standards which includes all the member states wishes for the different types of pressure vessel in use.

New European Standards

  • EN1975 Seamless Aluminium Tanks
  • EN1964-1 Seamless Steel Cylinders

Older British Standards

  • BS5045 pt3 for Seamless Aluminium Cylinder
  • BS5045 pt 1 for Seamless Steel Cylinders.

T6351 Aluminium Alloy Scuba Cylinders (requiring NDT) identification guide

  • All HOAL
  • EC type prior to 1992
  • BS 5045 Part 3 prior to 1994
Are made from 6351 alloy. The date is stamped on the cylinder
Alloys in later production are   • Identified by a letter code adjacent to the standard number
    A = 6082, B = 6351 and C = 6061
    e.g. BS 5045/3/C/S = 6061 alloy
The current approved UK IDEST stations listing is given here http://www.sita.org.uk/idestmembers.html

SCUBA Cylinder Manufacturing Specifications for testing to BS/EN/CGA limits
Located in the technicians password protected area - <click here to download>

3.    Thailand

Thailand represents one of the largest and fastest growing scuba destinations world wide, and has good legislation in place for the testing high pressure cylinders.

TIS (Thai Industrial Standards) booklet TIS 358-2531 (1988) "Standards for use and maintenance of compressed gas cylinders" ISBN-974-8112-29-2 uses hydrostatic methods similar to that used in USA, European and UK standards.

This booklet is currently only available in Thai language (click image to download).

Key points from this standard voice a '3 year' periodicity for hydrostatic testing, and that condemned cylinders must be 'cut in half' to prevent them from being used again.

Sadly, given the size of the Thai recreational Scuba Market consisting of more than 600 Dive Centers, this test standard is almost unknown, and government enforcement of it's procedures is practically non-existent.

Thai Industrial Standard 358-2531 Standard for use and maintenance of compressed gas cylinders.

download Thai Industrial Standard 358-2531 (ISBN 974-8112-29-2) 1.6Mbyte

A comprehensive examination of the different International techniques outlined above is covered during the ASSET Cylinder Inspector Pt1 & Pt2 course training.

Luxfer cylinders web site linkCatalina cylinders web site link

Both the manufacturers above have excellent web sites contain the latest up-to-date information and news on scuba tanks. 

Special Notes on Fibre-wrapped Composite Cylinder Types

fibre hoop wrapped composite scba cylinder

Unlike most steel or aluminium cylinders, fibre wrapped composite types have quite a short pre-defined life span of usually only 15 years.

Hydrostatic re-test periods are similar to metal cylinders of between 3-5 years, but the number of times you may subject the cylinder to hydrostatic test may also be limited. some types permit only 3 hydro test attempts following manufacture, and then the cylinder must be condemned.

Contact the manufacturer directly if in any doubt about the latest test methodology for these very special cylinders. The following represents typical test/re-test data for this cylinder type.

Lifespan:-                                     15years only
Hydrostatic re-test period:-             3 years
Hydrostatic Test Pressure:-            5/3 of Working Pressure
Permanent Set allowed:-                5% of volumetric expansion
Hold duration at Test Pressure:-     30secs minimum (most testers hold the hydrostatic test pressure for 60 secs )
Cylinder Marking:-                         No metal stamping on the cylinder body is allowed at all
                                                  
The re-test station verifies the hydrostatic test pass by affixing a custom label with the test station mark,month and year, sealed onto the cylinder body with epoxy resin
 


DIY Hydro test Rig manufacturing Information

Training in Visual inspection plus the required test equipment and tools is relatively inexpensive to obtain. However, hydrostatic test rigs costs are very expensive and cost around US$15,000 minimum.

If you have the formal engineering skills and fancy building your own hydro rig for a fraction of the cost.


Download the engineering drawings for a scuba tank hydrostatic test system here



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