Volumetric Testing & New Product Advances Volumetric Hydrostatic Testing
By Charles Grenci, President
1. The Basics:
A condensed primer providing an overview of the procedure and equipment.
Do you remember when Jaws lost its appetite when a SCUBA cylinder failed
the gunfire test? The myth busters demonstrated that what happened to
Jaws could happen to anything or anyone in proximity to a compressed gas
cylinder when it suddenly fails to contain the pressure inside. If the
cylinder failure is in proximity to other pressurized cylinders, a
domino effect can create multiple powerful explosions. It may be helpful
to have some kind of information about just how much energy is contained
in a compressed gas cylinder to give people an appreciation for the
value of testing them periodically.
Fortunately compressed gas cylinder accidents are rare in most
places. We at Galiso Incorporated are thankful that we have had the
opportunity for 45 years to participate in the process of testing
compressed gas cylinders around the world. People use the equipment that
we make to verify that gas cylinders can safely contain the pressurized
gas that the cylinder provides. The equipment we make is used to verify
that a cylinder is safe to use by measuring the growth characteristics
of a cylinder that is pressurized beyond its normal working pressure.
Compressed gas cylinders are designed with a safety factor that is
measured by our equipment in the following way. A compressed gas
cylinder is pressurized with water to a pressure that is higher than its
normal working pressure where the cylinder may: A) do nothing which is
the best case, B) stretch slightly within the required tolerance, which
is acceptable, C) stretch beyond the tolerance, which fails the cylinder
from service, or D) explode inside the test jacket. The test jacket is
designed to safely contain the force of the hydrostatic explosion.
The force of a hydrostatic explosion or burst is minimal compared to a
pneumatic explosion due to the use of water, not air as a pressure
medium. This is due to the minimal compressibility of water vs. the
highly compressibility of the gas that the cylinder normally contains.
Cylinders should receive a complete external and internal visual
inspection prior to a volumetric hydrostatic test. A typical
volumetric hydrostatic test (VHT) is comprised of the following steps:
1.
De-valved and filled with water
2.
Connected to a test jacket sealing apparatus and placed inside a test
jacket that is full of water.
3.
The temperature of the water inside the cylinder and outside the
cylinder in the test jacket should be verified to be within 4 degrees F
of each other, or the test results will be affected.
4.
The expansion zero value is established (fig 1).
Figure
1
VHT Zero Point
5.
The pressure inside the cylinder is raised to the required test pressure
for a required time, causing the cylinder to grow in size. The cylinder
expansion at test pressure is then recorded (fig 2).
Figure
2
VHT Pressure Hold / Total Expansion
6.
The pressure is released and the cylinder should return to a required
percentage of its original size. When the de-pressurized cylinder
expansion is stable, a permanent expansion value is recorded (fig 3).
Figure
3
VHT De-pressurized / Permanent Expansion
7.
The cylinder is drained of water and dried.
8.
The cylinder is then re-valved and stamped.
The amount of water forced out of the test jacket as a result of the
cylinder's growth during the pressurization is measured in an expansion
measuring device and compared to the amount of water left in
the expansion measuring device when the cylinder is depressurized. The
amount of water left in the expansion measuring device corresponds to
the amount that the cylinder was permanently deformed by the test
pressure. Generally, if the cylinder returns to within 10% of the amount
it expanded while pressurized, the cylinder passes the test.
Cylinders that pass both the visual inspection and the hydrostatic test
may be stamped with the re-qualification marks, and can be charged and
offered for transportation for 3-10 years depending on the type of
cylinder. The pass/fail criteria for some cylinders differ. As an
example most composite cylinders must return to within 5% of the
amount they expanded. However, the new carbon fiber composite
cylinders fail based on their elastic expansion. When a cylinder exceeds
the expansion limits for the retest, it indicates that the cylinder has
yielded, and the cylinder must be condemned.
This type of test procedure is often referred to as "hydrostatic
testing" or "hydrotest". Technically there are many types of hydrostatic
test applications that are unrelated to the cylinder test described
above so for the purpose of this article we will refer to this type of
testing as "volumetric hydrostatic testing" or “VHT”.
The answer to this question is multi-faceted and so we will attempt to
answer this question in more than one way.
First, in many applications VHT is required by government or industry
regulations so there is no choice. There are regulations that apply to
cylinder manufacturing that require 100% of all manufactured high
pressure cylinders that are greater than two inches in diameter to be
tested by VHT to meet Department of Transportation (DOT) regulations.
Second, there are certain types of cylinders that ultrasonic equipment
cannot test for defects at the present time. Composite cylinders are a
fast growing segment of the cylinder business in applications like self
contained breathing apparatus cylinders, medical oxygen cylinders,
aviation cylinders, CNG and Hydrogen fuel cylinders, paintball gun
cylinders etc. Light weight is a primary advantage of composite
cylinders. There are ultra-light type 4 CNG cylinders that are
constructed from a thin plastic bladder with a small metal gas
connection boss and then wrapped with carbon fiber. In a composite
cylinder, the fiber wrap does most or all of the work of containing the
force of the internal cylinder pressure. Trying to find a flaw in the
composite structure with UT would be like trying to find a needle in a
haystack. This is an example of a cylinder application where VHT is
required for both manufacturing and re-qualification testing.
Some readers may want to know why Galiso does not offer UT equipment for
testing cylinders. The answer to this question is multi-faceted as well.
Shortly after my father, Carl Grenci, passed
away in 1980, I came back to work at Galiso. My father was very involved
in CGA and my mom and dad were involved in IOMA, NWSA and NAFED. At the
age of 21 I was able to sit in for my dad at CGA meetings with some guys
that were pillars in the industry like Ralph Tribolet of Union Carbide,
Milt Hillegas of Air Products, etc. I also began attending IOMA meetings
with my mom, La Nora. At one of the first IOMA meetings that I attended
with her in
It would be interesting to find out how many companies there are that
have an exemption to test cylinders with AE today. It is also noteworthy
that there are many cylinders that are still in service from the early
1900's, so his comment about 5/3 test pressure damaging a cylinder might
be questionable. We responded to a later IOMA call for speakers
and I was able to present "Automating the Process of Hydrostatic
Testing" at the
Later in the early 1990's UT came on the scene as a potential
replacement for VHT. FIBA obtained an exemption to perform UT on
cylinders and began offering licenses to customers who were interested
in the potential cost savings that UT can provide. Airco, Dapco, and
Galiso submitted a joint application for exemption to DOT and were
rejected. Dominic Pagano of Dapco is the inventor of the liquid filled
wheel that is used to perform UT on railroad rails. This was the second
time we tried to get on board with a technology that was going to
replace volumetric hydrostatic testing. Things got real interesting when
the DOT sent up a test balloon saying that VHT would no longer be an
acceptable method and all cylinders re-qualification would be UT. In a
real life "Mr. Smith goes to
Having been rejected by DOT, Galiso sat on the sidelines of the UT
playing field and watched FIBA and others run their plays. The first
"real" machine that I saw for performing UT on cylinders was created by
a pair of guys named Mike Gorman and Steve Ziola of Digital Wave. They
created a very viable UT machine and then sold the rights to a company
called SCI (not the cylinder maker) which made a real mess of things,
and now I believe that Mike and Steve have bought back the rights to the
product and are back in the cylinder re-qualification business. If
Galiso ever does offer a UT product, I hope it is in cooperation with
Mike and Steve. It is noteworthy that they are experts in both AE and
UT. Their site address is
www.digitalwavecorp.com.
We nearly partnered with Digital Wave, when an opportunity came along to
provide Thunderbird Cylinder in
UT is not an actual strength test. In the case of heat treatment damage
this is a major problem because sometimes cylinders are in fires or
people use baked paint finishes that destroy the heat treatment
properties of the cylinder. UT and Eddy current will not catch a soft
metal problem which is one reason why VHT is required in manufacturing
to check the performance of the heat treatment operation.
Perhaps this analogy is appropriate. You need someone to lift 100 pound
boxes so you A) send him in for a UT test and the results show that he
has muscles that are big enough and are free from any detected
flaws. The problem is muscle mass and muscle power are variable and with
any imaging equipment some flaws go undetected. The same size vs.
strength issue is true of materials like steel and aluminum, or B) ask
him to lift a 160 pound box and he can..... this Very Heavy Test proves
they can readily lift 100 pound boxes as long as they are not injured
lifting 160 pounds.
UT is accepted as a replacement for VHT by exemption only. UT is not an
approved cylinder test method even after over 10 years in the exemption
phase which is noteworthy.
3. The Position VHT and UT occupy in the market
The U.S. DOT currently lists 34 facilities that are performing UT out of
2411 re-testers. UT has some tremendous cost savings potential for the
cylinder industry. The problem is that UT does not actually strength
test the cylinder to establish a safety factor. Not having to de-valve,
then fill, then test, then drain and dry, and then re-valve is
a significant advantage of this technology over VHT.
There are some applications where UT really shines, like specialty gas
cylinders where the contents are dangerous and the process of VHT is
impractical. The statistics above show that UT has not become widely
accepted as a method of cylinder re-qualification. It is noteworthy
that UT has been in the exemption phase for over a decade with a low
number of facilities performing this type of test.
We are in the beginning stage of introducing the Recortest 4 series as a
standard product. We have been developing this product series with beta
customers for two and a half years and the recent Rec4 installations in
Figure 4 Rec4 VHT Calibration Screen Figure 5 Rec4 VHT Data Entry Screen Figure 6 Rec4 VHT Pressure & Expansion Graph Screen Figure 7 Rec4 VHT Results Screen Figure 8 Rec4 VHT Diagram of System Status Screen Figure 9 Rec4 VHT Visual Inspection / Eddy Current Test Screen Figure 10 Rec4 VHT Mfg Cylinder Weights Screen
The Galiso programmable logic controller (PLC) network control, working
with the Galiso operator interface that runs on Microsoft Windows XP
operating system, leverages the communication capabilities of the
internet (figs 11 & 12). When connected to the internet, the Rec4 offers
remote support capability. We are able to operate, service, and support
networked R4 systems from our office in
We are often able to accommodate a software change request from our
customers in one day. In the beta development cycle this capability has
allowed us to report bugs on a foreign installation and have them fixed
while we sleep, thus enabling our technicians to be ready to test when
they arrive to work the next day. The video camera on the Rec4 allows
users to make free video calls to other camera-equipped computer users
worldwide. This free communication medium has been a real asset in
building meaningful customer relationships. The quality of video calls
has improved steadily during the Rec4 beta timeframe. The Rec4 offers
bar code capability, thereby allowing easy entry of cylinder information
to increase the accuracy and speed of data entry.
Figure
11
Galiso Network PLC Control for Lam PTX Figure
12
Galiso Network PLC Control for Lam PTX
Automatic email and verbal communications, test results, and error
messages are automatically generated and sent to a distribution list.
Automatic emails make it easy to keep track of system
operations. Messages are also announced on the Rec4 sound system
as verbal messages. The voice of our programmer,
We have employed 3D solid modeling software in the design and
development of the Rec4 control console and test station options (figs
13-16). We hope to offer many advanced service features with the solid
models to our customers, such as enhanced training images to help them
understand system operation and function, and also 3D Solid model parts
identification for repair and maintenance. Models are easily viewed from
any angle or magnification.
Figure 13 Recortest 4 Control Console 3D Model Figure 14 RSP-10DA VHT Pressurization Module and RSP-25DA Burst Pressurization Module Figure 15 Automated VHT Station for Small Cylinders Figure 16 HFP-8k Cycle Test Pump Module
5. Growth areas:
New applications and geographic targets.
Our traditional product line is focused on the needs of cylinder
re-testers worldwide, and this still remains a primary market segment
for our company. However, there have been significant orders from
cylinder manufacturers around the world for the Rec4 PLC-controlled
systems due to the Rec4's ability to provide multiple hydrostatic,
cycle, and burst test modules that can operate simultaneously, providing
increased efficiency and productivity.
Airline servicing centers worldwide that wish to service airlines under
the jurisdiction of the Federal Aviation Administration (FAA) must test
according to U.S. DOT regulations. Therefore, most of the world's
airlines are a primary target market for VHT. In this market segment,
we have a truly global market wherever reliable air transportation is
involved. We hope that the network control capabilities of the
Rec4 will be desirable in this market where quality documentation of
testing procedures and results is an important requirement.
We have VHT systems in over 100 countries worldwide, and this existing
customer base is a target market for those customers wishing to upgrade
their existing systems to incorporate Rec4 technology and capabilities
into their current testing stations. We plan to introduce Rec4
PLC-controlled upgrades this summer to customers all over the world. The
Galiso Recortest 3 generation of VHT technology was first released in
the 1980's, so we hope that the Recortest 4 series of hydrostatic
testing products will provide significant benefits to our customers, and
that there will be good demand for Rec4 systems and upgrades to both new
and existing customers worldwide.
As we have mentioned earlier, composite breathing air cylinders come
under regulations that require VHT testing, so VHT is the testing
standard for these types of cylinders. We have a new automated loading
system that provides for simultaneous testing of four cylinders,
including automated filling and drying stations that are all enclosed in
a multiple filtered water recirculation station. This all-inclusive
automated system is in operation at three cylinder manufacturing sites
and is providing great efficiency gains and high throughput with reduced
labor requirements. One operator can test between 35 and 40 manufactured
cylinders per hour using this new automated system. The VHT for
composite cylinder manufacturing requires an autofrettage pre-test.
We are looking forward to testing the throughput of this testing station
with medical aluminum cylinders, and we estimate that in this
application a single operator can VHT re-qualify an estimated 50-60
cylinders per hour.
The key company initiative at the present time is trying to discover
ways to enhance the quality of our work experience, which is very
important to me at this stage of my life. I love that we are moving
toward an environment where it is understood that people make mistakes,
where finger pointing is discouraged, and where lending a helping hand
to a fellow colleague to overcome a mistake or problem is encouraged. I
am thankful to be working in an environment where God is working
miracles in our relationships with our suppliers, customers and each
other. We are enjoying the combination of leisure activities like
poetry, music, and art with our business activities. Jonathan is a very
gifted poet, and it is wonderful to have the experience of writing
poetry with him to capture some of our experiences traveling together.
His son Joel, age 13, wrote this poem last year. I quote it often
because I hope to live this way:
The Credibility of Time
Credible, credible cried the clock as the hours ticked like chimes
If I'm not mistaken every second taken is lost to the plots of time.
So don't be preempted by Time's cruel plot
Discontent in disarray,
Rather be credible, enjoy what you've got
If not Time will take it away.
We have had some wonderful experiences with our initial Rec4 customers
that have been life-changing for us and for them. We have also had some
involvement with elementary school classes that has been a real
blessing. Our hope is to leverage technology to enhance our
relationships, and it amazes me that we can video call anywhere in the
world for free. Jonathan's brother Dan works with us, and he recently
coined the term "Rec4 connect" when we were on a video call talking
about how meaningful relationships are becoming our primary goal. Here
is a summary of what we hope that "R4 connect" will combine into a life
giving experience for all involved:
My father believed that time was more
valuable than money and that money is a reward for well used time. I
would say that another significant corporate initiative is well used
time. We hope to replace corporate profitability with meaningful
personal connections as the top objective of our corporate mission.
We still have profitability and technical excellence as key goals, but
the Rec4 connect approach highlights the personal and relational nature
of our business by elevating meaningful human interaction and personal
connections as a premier corporate priority in all aspects of our
business. As a result of this, our personnel will be encouraged to
view working colleagues, vendors, and customers as people who have
hopes, fears and dreams and as potential life-long friends. We are
hoping to stop perceiving them as necessary business intermediaries to
achieve economic goals. We hope to use web-cams and internet technology
to enhance interpersonal communications with traveling personnel and
customers worldwide and become a tangible example of how the R4
connect approach can be implemented technically to enhance relationships
meaningfully. A benefit of doing business this way is that it is
more fun and more rewarding for everyone when we connect.
So far the Rec4 connect approach has been well received by our customers
and has yielded both tangible and intangible results. The international
market has been growing steadily for us over the years and now
represents about 40% of our revenues and has contributed to an
approximate 24% increase in total sales. Due to the need for
volumetric hydrostatic testing systems wherever high-pressure gas
cylinders are manufactured or re-qualified according to DOT or
equivalent standards, the marketplace for our testing systems and
products is growing worldwide. With customers in over 100
countries worldwide, we are thankful to be in a position of leadership
in volumetric hydrostatic testing systems. In the last year, over
90% of the new Rec4 systems have been installed in foreign countries,
and it has been both challenging and rewarding to serve the global
marketplace.
During this time we have enjoyed increasing personal relationships with
school classes and educational partners. We hope to have increased
involvement in situations where academic data and knowledge are acquired
and transmitted in real-life, work experiences where learning becomes
fun,
relevant and part of a life-long process. This educational
interchange includes the company:
1) Adopting grade school classes for the school year
2) Participating in school-to-career exchanges
3) Offering work internships for high school and university
students
4) Writing white papers with input from collaborators around the
world
We have also been able to provide a relational work environment that
helps individuals in recovery to rebuild their lives with human
connections that are vital to personal health. As a community
employer, we have been able to offer employment opportunities to
individuals who are faced with challenging personal addictions or
difficult personal histories. In this way, we are hoping to
provide opportunity to hurting people in our community at large.
7. Examples: Exciting new customer installations
MCS
MCS, formerly Mannesmann, is one of the world’s oldest cylinder
manufacturers. MCS currently manufactures some of the most
advanced light weight type 4 composite cylinders for automotive CNG fuel
and breathing apparatus applications. They are the first Rec4 VHT
customer and recently installed a second R4 system with high volume
electric pumps for cycle testing and a 25,000 psi RSP pump for burst
testing.
The first Rec4 installation at MCS was a conversion upgrade of an
existing Recortest 3 system that was not able to perform a reliable
automated pressurization of the 190 liter type 4 composite cylinders
that MCS produces (fig 17). Type 4 cylinders are plastic containers with
metal gas connections that are fully wrapped with carbon fiber and as
such have pressurization behavior that is quite different from all other
cylinder types. It was in response to this problem that the decision was
made to try the same Galiso PLC that we use to control the Galiso HGS
process on semiconductor etching tools, along with some valves and
miscellaneous parts to see if we could solve the problem that MCS was
having and to establish a common control platform that leverages the
work we've already done in the semiconductor industry.
When we arrived in
Figure
17
Rec4 VHT #1 Type 4 Large Composite - MCS International
Figure
18
Rec4 Beta #1 development "Lab"
The three week conversion installation took place in December of 2004,
and the first night we were there we walked into a restaurant for dinner
where the man behind the counter welcomed us in perfect English. The
restaurant proprietor, Henry Lindenau, has become a good friend and we
have enjoyed some wonderful times with Henry and Stefan Limke, who is
the engineering manager for MCS.
This conversion installation was performed by Rick Wright, Chris
Hinchey, and Chuck Grenci. Chris Hinchey is a distributor for Galiso
products located in
On the day that Rick returned to the
Thunderbird Cylinder,
Thunderbird is one of the larger cylinder re-qualification facilities in
the U.S. Thunderbird obtained an exemption for UT testing and purchased
a machine to UT test cylinders, but later opted to use Rec4 VHT for
testing small aluminum cylinders (fig 19). This is noteworthy in that
small aluminum cylinder testing is one of the best applications for UT.
Their Rec4 VHT is able to test 80 cylinders per hour with 4 test
operators. This includes de-valve, inspection, fill, test, dry, stamp,
and re-valve.
Figure
19
Rec4 VHT #2 Medical Aluminum - Thunderbird Cylinder
Giant Bicycle Company/Compositech,
Giant Bicycle is one of the world's largest bicycle manufacturers and
has developed a specialty in manufacturing light weight composite
structures. They are working to produce carbon fiber wrapped cylinders
for the paintball industry. This was the first Rec4 station to provide
control for multiple test stations (fig 20).
Figure
20
Rec4 VHT/Cycle/Burst - Giant Bicycle Ctech Division
Scuba Service,
Scuba Service is using Rec4 VHT to test composite self contained
breathing apparatus cylinders (SCBA) and steel self contained underwater
breathing apparatus (SCUBA) cylinders. The company is owned by Ronnie
and Peggy Desmet. The test shop is located behind their home and is a
unique example of a Rec4 VHT in use by a small family owned business
(fig 21).
Figure
21
Rec4 VHT - Scuba Service
Advanced Material Systems,
Advanced Material Systems is another
Figure
22
Rec4 Automated VHT for Small Composite Cylinders - Advanced Material
Systems
Asahi Seisakusho, Iwatsuki
Asahi Seisakusho is a cylinder manufacturer in
Figure 23 Rec4 VHT Automated Small Composite Cylinder Test Station - Asahi Seisakusho Figure 24 Rec4 VHT Asahi Seisakusho Test Shop
Abdullah Hashim, Jeddah Saudi
Abdullah Hashim in
Figure
25
Recortest 3 Components Being Replaced by Rec4 - Abdullah Hashim
Industrial Gases
Crossfire Paintball,
Crossfire Paintball is the oldest manufacturer of valves for paintball
guns and operates a DOT certified CFFC (carbon fiber, full wrap,
composite) manufacturing facility. They use a Rec4 VHT automated
4-station system to VHT qualify the cylinders that they manufacture.
Ragasco, Raufoss
Ragasco is perhaps the most advanced manufacturer of composite cylinders
for LPG and CNG in the world. They operate a fully automated production
facility that is state-of-the-art. They are using a Rec4 cycle and burst
station for testing CNG cylinder designs in preparation for high
production manufacturing.
Japan Airlines Airtech is one of the newest Rec4 installations and is
designed with stainless steel test jackets for testing aircraft
cylinders. Working with JAL- Airtech is a great opportunity to explore
the potential advantages of the Rec4 platform in Aircraft service
applications (fig 26).
Figure
26
Rec4 VHT Airline Service System -
At the time of this article, 12 Rec4 systems are in operation - 3 in
8. A look ahead:
A glimpse of our R&D efforts and our vision for the future of
hydrostatic testing.
We hope that the flexible Rec4 network PLC control and operator
interface that we have written for the windows operating system combined
with a growing number of standard stations for VHT, cycle, and burst
testing will allow us to respond quickly and competitively to a variety
of opportunities in the testing of compressed gas cylinders. We would
like to explore hydrostatic pressure applications outside the cylinder
industry like washing cars and oil rigs.
We desire to employ the concepts that we have developed for automated
movement of small cylinders through the VHT process to stations for
large cylinders. Using the high output electric pumps that we have
engineered and supplied for cylinder cycle test applications in
volumetric hydrostatic test applications, we hope to increase test
throughput for large cylinders where pressurization time is a
significant factor. The Rec4 has the ability to test four
cylinders simultaneously compared to the Rec3's two (in limited custom
configurations). This capability provides increased VHT throughput for
customers who need it. Machines that work well can be rewarding and fun
to operate, and we hope to refine and fully apply the various
capabilities of the Rec4 to make cylinder testing an easy, reliable and
enjoyable experience for our customers.
Overall, it is our hope to integrate our new technologies within the
framework of our "Rec4 connect" approach to plant and water
relationships with suppliers, customers, and employees...and then look
for God-given growth. The cultural impact
of the "Rec4 connect" approach on daily operations is that corporate
resources are directed at accomplishing meaningful relationships that
will provide a better foundation to build upon than profitable business
exchange.
Galiso, Inc.® 1-800-854-3789/+970-249-0233 |