Emerson Fisher easy-e ED, Fisher easy-e EZ, Fisher YD, Fisher YS Data Sheet

Product Bulletin

59:045
October 2006

Gaseous Oxygen Service

Material Guidelines for Gaseous Oxygen
Service

All organic and inorganic materials will react with
gaseous or liquid oxygen at certain pressures and
temperatures. The reaction that occurs can cause a
fire or an explosion. Because of these inherent
dangers, process system design and control valve
material selection are extremely important.

Oxygen service has many inherent hazards and
requires careful and knowledgeable design of
the process system. The information and
guidelines presented here are intended to help
the user; however, other factors such as service
conditions and process system design must be
considered to properly select materials that will
handle this gas in a safe manner.

Many of the materials commonly used in control
valves have ignition temperatures above the normal
flowing temperature of gaseous oxygen. Ignition of
these materials by normal flowing temperatures is
generally not the danger. The danger is in the
ignition of these materials by abnormal, localized
high temperatures. Listed below are some of the
common causes of localized high temperature. This
list has been compiled from the best information
available, but does not necessarily contain all the
hazardous conditions that might be encountered in
oxygen service applications.

Common Sources of Localized High
Temperature

copper-base alloy material should be used for valve
body and trim parts in contact with the flow stream.

Foreign Particle Impingement

A foreign particle, such as weld spatter, that is being
carried in the flow stream and that strikes the valve
trim or the valve body wall might have its kinetic
energy transformed into sufficient heat to raise the
impinging particle or the material it strikes to its
respective ignition temperature.

Ignition by Already-Burning Material

An organic valve disk, for example, that has already
been ignited by foreign particle impingement will
release sufficient heat to ignite surrounding metallic
materials, thus initiating a serious fire.

Vibration

A part that is caused to vibrate, usually by the
flowing velocity, might generate enough heat from
internal friction to raise its temperature to its ignition
point.

Adiabatic or Rapid Compression of Gas

Opening a valve to pressure the downstream system
will result in the compression of the gas in the
downstream system. If this is done rapidly, it can
result in abnormally high gas temperatures, which
might ignite material in the valve and piping system.

Flow Velocity

All valve materials should be suitable for oxygen
service, and material selection should meet the
velocity criteria, such as set by the Compressed Gas
Association Pamphlet G-4.4 (copies can be obtained
from Compressed Gas Association, Inc., 500 Fifth
Avenue, New York, NY 10036). In general, if the
velocity through the port of the valve can exceed 61
meters per second (200 feet per second), only

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Static Electricity Discharge

The flow of gas across the trim of a ball, butterfly, or
eccentric disk valve might generate a static charge
on the trim. Because these valves inherently do not
have a good grounding path from the trim to the
valve body or from the valve body to the pipeline,
use proper provisions and care for their grounding.
Failure to do this might allow a discharge spark
between the trim and valve body or between the

D100071X012

Gaseous Oxygen Service

Product Bulletin

59:045

October 2006

valve body and adjacent piping, igniting the
surrounding material.

Conclusion

This list shows that many of the hazards arise from
the velocity of the flowing gas. For this reason, it is
imperative that the system be designed such that
flowing velocities will be low.

Organic Materials

Organic materials have ignition temperatures below
those of metals. Use of organic materials in contact
with oxygen should be avoided, particularly when the
material is directly in the flow stream. When an organic
material must be used for parts such as valve seats,
diaphragms, or packing, it is preferable to select a
material with the highest ignition temperature, the
lowest specific heat, and the necessary mechanical
properties.

Lubricants and sealing compounds should be used
only if they are suitable for oxygen service and then
used sparingly. Ordinary petroleum lubricants are
not satisfactory and are particularly hazardous
because of their high heat of combustion and high
rate of reaction.

Resistance to Ignition in Oxygen

Materials are listed in order from hardest to ignite to
easiest to ignite.

D Copper, copper alloys, and nickel-copper alloys

--most resistant

D Stainless steel (300 series)

D Carbon steel

D Aluminum--least resistant

Rate of Reaction

Materials are listed in order from slowest rate of
combustion to most rapid rate of combustion.

D Copper, copper alloys, and nickel-copper alloys

--do not normally propagate combustion

D Carbon steel

D Stainless steel (300 series)

D Aluminum--burns very rapidly

Note that stainless steel, once ignited, burns more
rapidly than carbon steel. Nevertheless, the
austenitic grades (300 series) of stainless steel are
considered to be much better than carbon steel
because of their high resistance to ignition.

The approximate ignition temperatures in 138 bar
(2000 psig) oxygen for a few organic materials are
shown in table 1.

Table 1. Typical Ignition Temperatures

TYPICAL IGNITION

MATERIAL

PTFE and PCTFE
70% Bronze-filled PTFE
Fluoroelastomer
Nylon
Polyethylene
Chloroprene and Nitrile

IN 138 BAR (2000 PSIG) OXYGEN

TEMPERATURE

_C _F

468
468
316
210
182
149

875
875
600
410
360
300

Metals

The selection of metals should be based on their
resistance to ignition and rate of reaction. Following
is a comparison of these two properties for some
commonly used valve materials.

2

Suggested Guidelines

Consider the following guidelines when selecting
process equipment for gaseous oxygen service.
These guidelines are for customer use in selecting
appropriate equipment for oxygen service, and
neither Emerson, Emerson Process Management,
nor any of their affiliated entities assumes
responsibility for material selection.

1. All regulators and control valves should be
degreased and processed for oxygen service in
accordance with current Emerson Process
Managementt or customer specifications. Suitable
lubricants, anti-seizing compounds, gaskets, and
packing are included in Fisherr Specification FGS
8A11, Cleaning, Processing, and Handling
Equipment for Oxygen Service.

2. All metals in contact with oxygen in the main flow
stream should be of appropriate materials suitable
for the given oxygen service.