HANDLING HIGH HANDLING HIGH PRESSURE CYLINDERSPRESSURE CYLINDERS

UMAINE Scuba Cylinder Training Program

RegulationRegulation

• The Department of Transportation (DOT) regulates transport of high pressure cylinders

• Occupational Safety and Health Administration (OSHA) regulates safety in the workplace

• The Code of Federal Regulations (CFR Title 49: 172.700) mandates employees of companies involved in commerce who handle compressed gas cylinders to receive appropriate safety training.

RegulationRegulation

• Discussions with US DOT have determined that most organizations involved in scientific diving are not involved in commerce and are exempt from periodic training updates (local regulations or standards may re-impose this requirement).

• AAUS and NOAA scientific diving standards require all scientific divers to receive hazardous materials training for handling high pressure cylinders

HP Cylinder ConstructionHP Cylinder Construction

• Construction- generally steel or aluminum• Capacity- amount of gas that can be compressed into the

cylinder at its rated pressure (expressed in cubic feet or liters).

• Working pressure- pressure in a cylinder at its capacity (expressed in psi or bar).

Cylinder MarkingsCylinder Markings

• Data describing the cylinder must be clearly stamped on the shoulder of the cylinder

Image courtesy Best Image courtesy Best PublishingPublishing

Aluminum Cylinder MarkingsAluminum Cylinder Markings

Image courtesy Best Image courtesy Best PublishingPublishing

Steel Cylinder MarkingsSteel Cylinder Markings

Image courtesy Best Image courtesy Best PublishingPublishing

Cylinder ValvesCylinder Valves

• Valve types- K, J, H, Y• Valve connections- Yoke vs. DIN

Deutsches Institut für Normung German national standards organization.

• Valve features– O-ring– Burst disc– Function

KK

JJ

HH YY

Cylinder InspectionsCylinder Inspections

• Hydrostatic Inspection- performed after manufacture and at 5 year intervals

• Visual Inspection (VIP)- performed annually

• Internal inspections, hydrostatic tests, and repair work should be performed only by trained technicians

Cylinder InspectionsCylinder Inspections

• Damaged/flooded cylinders should receive a visual inspection before being put back in service

• A cylinder that has failed the visual inspection or hydrostatic testing process may never be returned to service and is considered CONDEMNED.

• Condemned cylinders should be made unserviceable (i.e. cut in two, hole drilled in the wall, threads destroyed, etc…)

Condemned CylindersCondemned Cylinders

• Do not use any cylinder that:– Is aluminum and has a rounded bottom– Have the manufacturing codes SP6576, SP6688, or

SP890 stamped into the cylinder– Have large dents, bulges, or lines of corrosion– Do not have a proper pressure relief device (burst disc)– Have manufacturing codes SP6498, E6498, SP7042,

or E7042 stamped into the cylinder unless the cylinder is also stamped with the code 3AL

• These were special aluminum alloys that were given the 3AL rating at a later date

Hazards and Handling Hazards and Handling ProceduresProcedures

• Treat all HP cylinders with R-E-S-P-E-C-T!• An 80 cubic foot cylinder filled to 3000 psi (207 bar) has

in excess of one million pounds of kinetic energy; sufficient power to blow apart brick walls, destroy vehicles, and injure or kill people.

Photo courtesy Photo courtesy connected.bc.ca/~baquatics/index.htmconnected.bc.ca/~baquatics/index.htm

Cylinder Hazards- Safe HandlingCylinder Hazards- Safe Handling

• Do not drop, abuse, modify cylinders• Use only for scuba diving and related purposes• Wear closed-toed shoes when working around cylinders• Use proper lifting techniques and dollies to minimize the

risk of personal injury• Open cylinder valves slowly• Do not put your body in the gas stream

– High pressure can force gas through the skin and into the body; bubbles in the circulatory system could result in an air injection injury and/or embolism

Safe Handling ProceduresSafe Handling Procedures

• Regulators or gauges may fail when a cylinder valve is opened – it is important to stand to the side rather than in the line of discharge to avoid the blast effect in case of failure

• Do not look directly at the face of any pressure gauge when turning on the cylinder because of the possibility of a blowout

StorageStorage

• Store charged cylinders in an upright position • Secure cylinders properly to prevent falling or rolling

– Chain or stout rope to sturdy object or wall– 3-point nesting method

• Store at temperatures not to exceed 130o F (54 C)• Maintain a clear egress path to avoid knocking over

cylinders

TransportTransport

• By hand– Carry with one hand on the valve– Do not stirrup or cradle cylinders– Do not place hand over orifice (air injection risk)

• By vehicle/boat– While in transit, cylinders should be secured– Racked, tied, blocked, etc.

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• A fill station consists of a source of high pressure gas, high pressure lines called whips that connect the gas source to the cylinders being filled, and valves and gauges to control and monitor the filling process

• Fill stations come in a wide variety of configurations, the specifics of operating a given system are beyond the scope of this presentation and require additional training

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• Diving cylinders and associated high pressure equipment are manufactured and tested to standards in order to ensure a high degree of safety when they are properly used and maintained

• Manufacturing standards and maintenance requirements do not eliminate the possibility of a catastrophic failure that could result in serious injury or death

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• 90% of all cylinder explosions occur during the filling process

• Operator error has been linked to many of these incidents

• Properly trained and attentive operators reduce their risk of being involved in a catastrophic incident

• Be familiar with the equipment you are working with and follow inspection requirements and safe operating procedures

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• Storage banks have specific pressure limitations and are secured to prevent them from falling

• Cascade filling involves equalizing the pressure in the cylinder being filled with the pressure in a single cylinder in a series of storage cylinders, moving to the next cylinder in the series and repeating the process until the desired pressure is reached

• Cascade filling is the most economical use of banked gas

Ph

oto

cou

rtesy

Ste

ve S

elle

rsPh

oto

cou

rtesy

Ste

ve S

elle

rs

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• Fill station valves can be of a metering or ball valve design– A metering valve provides for slow and controlled

pressure adjustments– A ball valve is either open or closed

• Caution should be taken when using ball valves, as rapid pressure spikes can occur

Ph

oto

s co

urt

esy

Glo

bal M

fg.

Ph

oto

s co

urt

esy

Glo

bal M

fg.

Corp

.C

orp

.

Metering ValveMetering Valve Ball ValveBall Valve

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• High pressure lines:– Pipes and hoses that carry high pressure gas should

be secured approximately every two feet and regularly inspected

Ph

oto

cou

rtesy

Ste

ve S

elle

rsPh

oto

cou

rtesy

Ste

ve S

elle

rs

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• The Fill Station Operator has the responsibility to reject cylinders that do not meet standards

• Before filling a cylinder:– Verify it has valid ICC or DOT stampings– Check for a current Hydrostatic Test Stamp– Check for a current Visual Inspection– Check for damage, corrosion, flooding, etc.– Check the working pressure of the cylinder– Check for a proper burst/overpressure disc

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• Before filling a cylinder:– Check the pressure in the cylinder and its contents

(air, nitrox, etc.)• Cylinders containing gas mixtures other than air

should not be allowed to equalize pressure through the fill whips with cylinders not containing the same gas; doing so modifies gas mixtures in all the cylinders and could compromise the safety of unsuspecting divers using them

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• Preparing to fill:– Open cylinder valve to blow out dust/water– Attach the fill whip to the valve– Close the whip bleed valve and open the cylinder

valve• If filling multiple cylinders containing the same gas,

open all cylinder valves and equalize the pressure between cylinders

– Open the fill whip valve – Open supply valve

Ph

oto

cou

rtesy

Ste

ve S

elle

rsPh

oto

cou

rtesy

Ste

ve S

elle

rs

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• Charge cylinders at 300-600 psig/min (20-41 bar/min) to prevent excessive heat buildup

• Never exceed the maximum allowable pressure for any particular cylinder

• Never perform maintenance or repairs on a cylinder valve while the cylinder is charged

Ph

oto

cou

rtesy

Ste

ve S

elle

rsPh

oto

cou

rtesy

Ste

ve S

elle

rs

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• A 3000 psi (207 bar) cylinder should take 5 to 10 minutes to fill

• Aluminum alloy cylinders should never be filled in excess of marked service pressure, and steel cylinders without a plus (+) after the current hydrostatic test date should also not be filled over their marked service pressure

Fill Stations and Fill Stations and Filling CylindersFilling Cylinders

• When the filling process is complete, bleed excess pressure from the fill whips, close all valves, shut off power to the compressor, and secure the fill station per local procedures