Page 30 - Apollo - Industrial Applications Guide

DEFINITION:

Webster’s New World Dictionary defines
CORRODE, Corrosion, Corrosives as:
1) to eat into or wear away gradually, as by rusting or by the action of chemicals,
2) to work upon insidiously and cause to deteriorate

Therefore, when a flowing medium, or environment, is said to be corrosive, one should take note and be very cautious in
recommending and/or selecting the materials of construction. Always ask what Valve types, and Materials, have been used in
similar services. When there is no history of services to fall back on, please contact the nearest Apollo Factory Representative, or
contact Apollo Technical Services Group direct.

INTRODUCTION:

In corrosive services it is important that all components of the valve be verified to be the proper material and compatible for the
intended service. ASME Section I, and ASME B31.1, require that a corrosion allowance be provided as a part of the minimum wall
thickness; whereas, other valve designs (WOG/CWP/MSS-SP 110) do not specifically address corrosion allowances.
Regardless, corrosion allowance alone, on a valve Body or Component, will not insure proper performance if the selected
materials are not resistant to the corrosive attack. The Compass Corrosion Guide is an excellent source for determining a
particular materials resistance to corrosion.
NACE, originated in 1943 by a group of eleven Chemical Engineers interested in the study of cause-and-effect of pipeline
corrosion. Today, this once small organization has grown to become a worldwide organization, and is now know as NACE
International, involved in most every form of corrosion and material requirements imaginable. One of those standards, NACE
MR0175 - Standard Material Requirements, is a commonly imposed/enforced standard within the oil and gas industry. At
Apollo®, we can offer a variety of our valves that meet the requirements of NACE MR0175.

CRITICAL NOTE: At Apollo®, we manufacture NACE valves that comply with NACE MR0175, 2000 Edition.
GENERAL NOTE: It is conceivable that some corrosive applications would include Fugitive Emissions requirements. It is important to look at the compatibility
of all the valves components not just the body material. You should take into account all items that come in contact with the media such as ball, stem,
bearings, springs, seats, stem packing, body seals and even fillers used in the seals. Sometime it is just as important to look at external components of valves
as it is the internal components. Even though the process itself may not be corrosive, the atmosphere sometimes can be very aggressive. Temperature
changes can make a huge difference in how aggressive the chemical attack can be. Once you reach a certain point, even a ten degree temperature increase
can mean the difference between acceptable or not. Also the state of the media plays a big part. Concentration of the media and things like whether a
substance is anhydrous or aqueous, wet or dry, crude or pure, fuming oleum or boiling, air free or aerated can greatly affect compatibility.

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