One of the most common questions I hear from both the field and from distributors has to do with recent OSHA Standard 1910.253(b)(4)(iii) and OSHA Standard NFPA 51 2-4.3.

1910.253(b)(4)(iii) – Oxygen cylinders in storage shall be separated from fuel-gas cylinders or combustible materials (especially oil or grease) a minimum distance of 20 feet (6.1m) or by a noncombustible barrier at least 5 feet (1.5m) high having a fire-resistance rating of at least 1/2 hour.

NFPA 51 2-4.3 – Oxygen cylinders in storage shall be separated from fuel-gas cylinders or combustible materials (especially oil or grease) by a minimum distance of 20 ft. (6 m) or by a barrier of noncombustible material at least 5 ft. (1.5 m) high having a fire resistance rating of at least 1/2 hour. The barrier shall interrupt all lines of sight between oxygen and fuel-gas cylinders within 20 ft. of each other.

Clarification is often needed in reference to construction sites, as OSHA seems to imply that if an oxygen and acetylene combination is secured on a welding cart, connected and ready for use, they could be considered to be “in use” and therefore not being stored. Let’s take it a bit further. The standard’s language can also be understood to indicate that the cylinders are being stored if they are not being used, even though they are connected for use on the cart.

Traditional cylinder carts have been used successfully for years to safely transport oxygen and acetylene cylinders to and from job sites, as well as to store cylinders when not in use. However, with the implementation of OSHA 1910.253, it became necessary to satisfy the standard. The answer came in the form of the firewall cylinder cart.

Firewall Protection
A firewall cylinder cart is designed to restrict a flame generated from one acetylene or other welding fuel-gas cylinder placed adjacent to one oxygen cylinder on the same cart. A triple steel baffle partition performs this function. The purpose of the partition is to restrict a flame generated by the acetylene or other welding-grade fuel-gas cylinder from heating the adjacent oxygen cylinder contents to such an extent that it causes expansion of the oxygen cylinder contents, which increases the PSI level higher than the DOT-prescribed safe pressure level. Should the oxygen cylinder contents be expanded beyond the DOT safe level, the expanded contents could activate the safety control burst disc, which would then allow oxygen to be added to the fuel-gas cylinder generated flame, causing a more intense or expanded flame.

One of the first attempts to satisfy the standard came with the introduction of cylinder carts that utilized a .25-inch steel plate separating the two cylinders. This did not do the trick as current Federal OSHA interpretations regarding firewall regulations state that a single .25-inch steel plate is not sufficient as a firewall, because it cannot protect the cylinder from excessive radiant heat emanating through the .25-inch steel plate for 30 minutes. For this reason, a firewall partition was introduced to the market. This partition is comprised of three separate baffles which create two exhaust vents at the top and two intakes at the bottom. This allows the heat generated from the welding grade fuel-gas flame of one cylinder to draw ambient air in from below, which drives the heated air up through the top vents. Thus, the heat transfer to the oxygen cylinder on a firewall cart is minimal, because the baffle design directs the heat upward, thereby prohibiting excessive heat from penetrating to the other side. This substantially reduces the probability that heat from the acetylene or other welding grade fuel-gas will radiate through the steel firewall baffle plates such that it reaches the oxygen cylinder and raises the oxygen contents above the DOT safety level.

Storage or Use?
So, with the solution in hand to satisfy the OSHA standard in the form of the firewall cart on construction sites, the question still remains: “How does one determine if a cylinder cart, fully loaded, connected and ready for use is storing cylinders or being used?” This is a very relevant question when you consider the safety aspects of this issue and the possible financial implications that could be levied against construction companies that are faced with this question.

Under the construction standard 1926.350 (a)(10), cylinders that are connected and secured in a cylinder cart are considered to be in use and not in storage if they are connected to a properly functioning regulator and as long as they are anticipated to be used within a 24-hour period, weekends included. The key word here is anticipated. How does one quantify this? The other side of the problem is that if the burning rig is not anticipated to be used within the next 24 hours, then the cylinders must be taken off the cart and stored properly and in accordance with OSHA standards as they relate to the proper storage of cylinders. This can be cumbersome and time consuming, and increases the risk of damage to the regulators.

My recommendation is to always play it safe. Safety is always first. If you feel that the interpretation of the standard applies to you or your customer, consider using a firewall cart, just to be safe.

(The opinions expressed in this article are solely those of the author. They should not be considered as advice.)

Meet the Author Frank S. Salvucci Jr. is vice president of Anthony Welded Products Inc., headquartered in Delano, California, and on the Web at www.anthonycarts.com.