IQS Newsroom Articles on Pressure Vessels
About Pressure Vessels and Pressure Vessel Manufacturers
Including: ASME
Tanks, Autoclaves, Kettles, Pressure
Tanks & Water
Pressure Tanks.
Pressure vessels most often contain fluids, vapors
or gases at pressure levels greater than that of atmospheric pressure.
Pressure vessels contain a wide variety of substances used for various
industrial applications including the chemical, pharmaceutical, food
and beverage, oil and fuel and plastic industries. The substance contained
and the industrial application of the pressure vessels determines such
design components as vessel material, size, shape, temperature and pressure
level. Vessel creation and maintenance consist of structured steps in
which the above factors are determined. When a substance is stored under
pressure, the potential for rupture and leakage exists. Improper vessel
design and maintenance increase the risk of pressure vessel failure,
posing a serious safety hazard. This risk increases when vessel contents
are toxic or gaseous substances. Engineers take precautions when creating
a pressure vessel to limit the occurrence of vessel failure. The division
of vessel creation into steps, which include design, construction, testing
and inspection, keeps safety hazards to a minimum.
In the design process, engineers determine the logistics of how pressure
vessel manufacturers will create the vessels. Engineers must determine
the pressure level, temperature, material components, size and shape.
Engineers also consider the corrosion and abrasion potential of the vessel
before deciding these factors. Pressure levels are also taken into account
before deciding upon a material and shape. Pressure vessel manufacturers
fabricate a range of pressure vessels; from a few hundred pounds per
square inch (psi) to measuring up to 150,000 psi. Temperature must also
be considered before deciding on a material, as materials like steel
are susceptible to damage from exposure to extreme temperatures. Materials
can include carbon alloy steel, stainless steel, titanium, zirconium,
aluminum, nickel alloys and niobium. Sizes range from small vessels holding
only a few ounces of a substance to very large vessels with up to a 95,000-gallon
capacity. Most pressure vessels are cylindrical; however, contents under
extremely high pressure are often placed in stronger spherical vessels.
Because of the above factors and the fact that pressure vessels can have
a temperature range that exceeds 750°F, safety is of large importance.
There are standard regulations and formulas to which the pressure vessel
manufacturers' designs adhere in order to avoid potential hazards
associated with pressure containment. The American Society of Mechanical
Engineers (ASME)
provides a Boiler and Pressure Vessel Code on which engineers base pressure
vessel design. Although the ASME Code remains the most common standard,
engineers also follow other codes, such as that of the American Petroleum
Institute (API). Rigorous analyses for complex pressure vessels are created
when standard design rules do not apply. In such instances, engineers
conduct intensive mathematical and scientific analyses to ensure design
and construction methods meet the stringent requirements of pressure
vessels: material, size, shape, temperature and pressure level of the
pressure vessel, as well as personal preferences.
Engineers usually create vessels using one of three processes. Forging
involves the formation of metal parts through the application of heat
and pressure. Welding involves melting two similar metals together. Brazing
involves the joining of metals by filling the space between them with
a nonferrous metal. Testing of the pressure vessel ensures design technique
success, proper vessel operation and certification approval. Regular
inspection remains necessary to ensure that the vessel continues to meet
industrial standards and safety requirements. The National Board of Boiler
and Pressure Vessel Inspectors remains the worldwide standard for pressure
vessel inspection, alteration and repair.
Types of Pressure Vessels
- are pressure vessels that meet the standards set by the American Society of Mechanical Engineers.
- are closed pressure vessels that use steam and high pressure to sterilize instruments.
- are a
type of pressure vessel that are used to bring about a physical change
in their contents. Examples of this are digesters, vulcanizers and rendering
tanks.
-
utilize fuel combustion to generate heat. Examples include boilers,
furnaces, gas water heaters and autoclaves.
- include
a variety of configurations of vessel equipment in which heating or
cooling is performed on one side of the vessel
and the opposite conversion on the other side. (http://www.heatexchangers.org)
- are pressure vessels that use steam to heat fluids.
- are vessels that hold contents at pressure levels greater than atmospheric pressure.
-
usually contain steam, which is then used to dry articles such as paper,
fabric or plastics. The materials are passed over the rotating vessel
via rollers to come into direct contact with the emitting steam.
-
are used to heat liquid to a moderate degree. Steam is distributed between
the inner and outer shells of the vessel and is used in the commercial
preparation of foods such as candy.
-
include air tanks, hot water tanks, propane or other gas tanks, which
contain contents under pressure when needed.
- are the least
common. They are any cylinder [shell] ratio that is 10% or more
the ratio of the thickness to the inside diameter.
- are one of the most common of the vessels. They are any
cylinder [shell] ratio which is 10% or less of the ratio of the
thickness to the diameter, or a pressure vessel is thinned walled if
the diameter is 10-times or more of the thickness.
-
are in contrast to those that are stationary. Examples of such are those
are road or rail tankers; propane and gas tanks are considered to be
in this category.
-
are not exposed to direct heat. Generated heat, if any, is produced
through electric heat or steam, and sometimes through the chemical reactions
of vessel contents.
- hold water at levels exceeding atmospheric pressure.
Common Terms Related to Pressure Vessels,
Pressure Tanks, Water Pressure Tanks, Autoclaves, Kettles, ASME Tanks,
Pressure Vessel Manufacturers, and Stainless Steel Pressure Vessels.
-
Device used for agitation of the product or substance found inside a
pressure vessel.
- The amount
of force the atmosphere exerts upon the earth's surface, measuring
14.7 psi at sea level.
- Primarily used in pressure vessels
with agitators. Commonly used to increase the amount of agitation or mixing.
- Pressure vessel that
heats water and creates and heats using combustible fuels or energy.
- Fracture
of steel associated with exposure to very low temperatures often in circumstances
in which stress levels have not exceeded yield strength.
- An increase
in pressure vessel shell thickness designed to compensate for the corrosion and
abrasion of certain pressure vessels; protective coatings and linings
are also added to pressure vessels to prevent corrosion.
- Permanent deformation
of steel caused by strength reduction resulting from exposure to high
temperatures.
- Extremely
low temperatures, ranging from -250° C to -100° C
(-418° F to -148° F).
- The maximum
internal and external pressure limits that a pressure vessel can withstand,
usually equivalent to 110% of pressure vessel operating pressure.
- The temperature
of the pressure vessel metal when the vessel is subjected to the design
pressure.
- Pressure vessel created
to sustain cryogenic temperatures.
- A nozzle made for
sanitary and low pressure applications. A ferrule contains an inset gasket
surface and is designed to work with clamps instead of bolting.
- Any substance, whether
liquid, gas or vapor, in which the particles move freely, resulting in
no permanent shape and low resistance to pressure.
- Pressure relief
mechanisms initiated with rapid pressure increases resulting from a fire.
-
Broad terminology for providing a pressure vessel or pressure tank with a means of temperature
control.
- Pressure
vessels in which both liquids and gases are collected.
- Test in which
pressure vessels are subjected to 150% of the design pressure.
- Diameter
of the pressure vessels measured from the interior of the pressure vessels surfaces. This
dimension does not include the material thickness.
- Lugs attached
to the outside of the pressure vessels specifically placed to help aid lifting of
the pressure vessels.
- Access port to the
internal region of the pressure vessels.
- Unit of measurement
equal to 1,000,000 pascals, used to express tensile strength and yield
strength.
-
Worldwide standard for pressure vessel inspection, alteration and repair.
- Unit of force producing
an acceleration rate of one meter per second per second on a one-kilogram
mass.
- The spout through which
fluid is released from or introduced into pressure vessels.
- The pressure
at which pressure vessels operate while in use.
- Unit of pressure measurement
equal to a Newton per square meter.
-
Unit that measures the amount of pressure applied to an object.
- Pressure relief
mechanism that automatically releases liquids from pressure vessels when
vessel pressure exceeds set pressure, and closes when the pressure level
returns to normal.
- Pressure relief
mechanism designed for single usage that instantly relieves pressure in
a pressure vessel. These can be used in conjunction with other pressure
relief mechanisms.
- Pressure
relief mechanism that automatically releases liquid and vapor streams
from pressure vessels when vessel pressure exceeds set pressure, and closes
when the pressure level returns to normal.
- Pressure relief
mechanism that automatically releases gases and vapors from pressure vessels
when vessel pressure exceeds set pressure, and closes when the pressure
level returns to normal.
- The predetermined
pressure at which a pressure relief device begins to discharge fluid.
- Small, cylindrical
pressure vessel component consisting of a bolted rim connected to the
body of the pressure vessel.
- The change in an object's
dimensions, resulting from the application of force.
- The force responsible
for causing a change in an object's dimensions.
-
Fracture resulting from the combination of corrosion and tensile stress.
- The maximum
stress level exerted upon a test specimen before the specimen fractures.
- The force applied
to a test specimen to produce strain.
- The end of a
pressure vessel, including flanged and dished, ellipsoidal, flat, conical
and hemispherical.
- The pressure
vessel body.
- Amount of stress
producing an inelastic strain in a pressure vessel. Exceeding the yield
strength can result in permanent deformation of the vessel.