| When exactly does my visual inspection or hydrostatic test expire? |
| A visual inspection expires one year following the inspection. A hydrostatic test expires five years following the test. Because neither a visual inspection sticker nor hydro retest mark show the day of the month performed, the practice in the SCUBA industry is that the valid period expires on the first day of the month shown. If you have an official written record including the serial number of the cylinder and the exact date of the inspection or hydro, the expiration date is at the beginning of the day indicated on the written record |
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| What is an eddy current exam? |
| This examination uses a tiny current of electricity and is performed on some types of aluminum SCUBA cylinders to assist in the detection of cracks in the threaded neck area. It alerts the inspector to specific locations on the neck threads that need further evaluation. The devices using eddy current technology are sold under the brand names Visual Plus, Visual Eddy, and Simple Eddy. The exam is notorious for false positives as a result of poor operator technique and is intended only to supplement, not replace, the visual inspection. Luxfer recommends eddy current tests be performed only on their aluminum cylinders made from 6351-T6 alloy. However, many dive shops require an annual eddy current exam on all aluminum cylinders before filling, regardless of the type of alloy. Eddy current exams are not meaningful on any type of steel. |
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| Does Benthic SCUBA require an eddy current test on all aluminum cylinders before filling? |
| No. We require an eddy current exam only on cylinders made from aluminum 6351-T6 alloy. |
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| Why do aluminum cylinders made from the 6351-T6 alloy require an eddy current test? |
| This particular alloy has a history of a phenomenon known as sustained load cracking (SLC) that can cause a cylinder to fail. Aluminum SCUBA cylinders manufactured in 1982 and 1983 require particular attention because the 6351-T6 alloy used during that period had a higher lead content which makes the cylinder more susceptible to SLC. By 1990, the US aluminum cylinder industry was using a different alloy, known as 6061-T6. There are no indications that the 6061-T6 alloy has problems with SLC, and no steel cylinder has ever shown problems with SLC. |
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| How do I know if my aluminum cylinder is made from the 6351-T6 alloy? |
As a general rule, you should suspect any aluminum SCUBA cylinder manufactured in the US before 1990 was made from the 6351-T6 alloy. However, different manufacturers ceased using the alloy for production of SCUBA cylinders at different times so the general rule is not precise. Luxfer phased 6351-T6 out over two years and had completely ceased using it by mid-1988, Walter-Kidde ceased SCUBA cylinder production using 6351-T6 in 1989, and Catalina never used 6351-T6. In 1994 the US Department of Transportation (DOT) issued a Safety Advisory Notice #94-7 which identified in detail most 6351-T6 alloy cylinders (including many non-SCUBA cylinders) manufactured in the US. In 1999 the DOT issued a followup Safety Advisory Notice #99-11 which reiterated and supplemented precautions regarding 6351-T6 alloy cylinders. You should consult these notices to precisely determine which cylinders are made of from the 6351-T6 alloy.
Markings:
DOT SP6498
DOT E6498; E7042; E8107; E7235; E8023; E8115; E8364; E8422
See Ontario Fire Marshal (OFM) And The National Institue For Occupational Safety and Healt |
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| Will Benthic SCUBA fill my aluminum 6351-T6 alloy SCUBA cylinder? |
NO, as of the Fall 2009, we reqrete that we will not fill any 6351-T6 SCUBA cylinder regardless of its age or composition.
Benthic SCUBA does not recommend renewing the visual inspection or hydro-static test for aluminum 6351-T6 alloy SCUBA cylinders because of problems with sustained load cracking (SLC) in those cylinders. We recommend that aluminum 6351-T6 SCUBA cylinders be removed from service. Luxfer, who manufactured the overwhelming majority of aluminum 6351-T6 cylinders between 1977 and 1988, had an exchange program for those cylinders that run throughout the 2003 calendar year. Owners could have returned their 6351-T6 alloy SCUBA cylinders to Luxfer in exchange for a $50-per-cylinder credit against the purchase of a new Luxfer SCUBA cylinder. Benthic SCUBA suggests that owners of 6351-T6 alloy SCUBA cylinders take advantage of Luxfer's exchange program. DO NOT BE FOOLED into purchasing a 6351-T6 alloy SCUBA cylinder from eBay, a yard sale, etc.. These cylinders are potentially deadly, have proven to be deadly and are the equivalent of a ticking time bomb. It's not of a matter of "IF" it will fail, but "WHEN". |
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| What cylinders require an interior inspection before Benthic SCUBA will fill them? |
Our fill station operators are trained to perform a cursory examination of each cylinder before it is filled. We require an interior inspection whenever we encounter a cylinder with:
> Leaks
> Rattles, sloshes, or other unusual noises
> Abnormal weight
> Zero pressure, i.e., completely empty
> Foul-smelling contents |
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| What cylinders does Benthic SCUBA refuse to fill? |
Regardless of what appears to be a valid evidence of inspection sticker or hydrostatic test stamp, we consider some cylinders unsafe to fill. We will not fill any cylinder with:
> Heavy corrosion, especially line corrosion at the boot
> Exterior damage, such as a dent, gouge, bulge, or deep pit
> Evidence of exposure to high temperatures, such as scorching
> Vinyl or other unusual or unrecognized coatings or paints
> Valve using a lead plug overpressure burst disk
> Attributes that would cause it to be permanently removed from service
> It is illegal in Canada to fill; visually requalify; or rehydrotest any cylinder that lacks a "TC"/"CTC" stamp that was manufactured after 01/1993. |
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| What cylinders should be permanently removed from service? |
According to the US Department of Transportation regulations, the Compressed Gas Association guidelines, or manufacturer recommendations, some cylinders should be permanently removed from service. Our fill station operators will not fill the following cylinders:
> Any with missing or illegible TC/DOT > required markings
> Any with a Condemned marking
> Any aluminum with a + mark
> Any aluminum with round or beveled bottom
> SP6688 Morris (Military Division)
> SP6575/6576 Kaiser Industry
> SP6020 Kaiser Industry
> SP890 Canadian Aluminum
> Any cylinder manufactured from 6351-T6 Aluminum |
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| Are there any exceptions to your cylinder qualification requirements? |
| We fill the small cylinders used in Buddy and Drager rebreathers. Although these cylinders lack a TC/DOT stamp, we fill them to a maximum of 200-Bar (3000 psi) if they have a current evidence of visual inspection sticker. |
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| Will you fill an SCUBA cylinder over 15 years old? |
| Yes. As of Winter 2002, if it meets all our other cylinder qualification requirements, we will fill any SCUBA cylinder regardless of its age or composition. |
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