|Mechanically Attached Pipe Fittings
More Cost-Effective Pipe Fabrication Through Standardization
Following the end of the Cold War, the Navy sought to lower the
cost of maintenance while maintaining fleet material readiness.
Repair of shipboard piping systems offered potential cost savings.
A typical ship contains miles of pipe and thousands of joints
carrying everything from fuel to steam. Shipboard pipe is joined
by various methods such as welding and brazing. When pipe and
fittings are installed in Navy ships, they must be tested for
quality and integrity to ensure performance and to protect the
health and safety of the ship and her personnel. As new pipe-joining
technologies emerge, they must be thoroughly tested and approved
before being used in U.S. Navy ships. Sometimes, this testing
process can delay the introduction of promising technologies for
years and preclude the realization of substantial savings.
In the 1980s, a new pipe-fitting technology, the mechanically
attached fitting (MAF), was developed, promising substantial improvements
over other existing pipe-joining technologies such as welding
and brazing. Several different types of MAFs were available from
several different manufacturers. These included axially swaged,
shape memory alloy (SMA), swage marine, bite-type, flared, and
elastic strain pre-load (ESP) fittings. Many MAFs offered easy
fabrication, high reliability, and lower installed cost. Within
the Naval Sea Systems Commands (NAVSEA) Auxiliary Equipment Division,
the life-cycle manager for pipe-fitting components recognized
an opportunity to save money and improve performance.
The Navy needed proof that MAFs could provide the same or better
integrity than brazing or welding before authorizing their use
in the fleet. Testing standards were needed to provide that proof.
The Navy initially began testing, approving, and procuring various
MAFs for the Navy using the test procedures provided by the individual
manufacturers. Different fitting types were subjected to different
tests and test requirements. The test procedures were informal,
sometimes inconsistent, and not standardized.
Some MAF manufacturers were not happy when their fittings were
tested under different tests than those used for their competitors;
they wanted a level playing field. In addition, procurement decisions
potentially were subject to protests because of the differing
test methods and acceptance criteria. Also, because the Navy tested
different fittings using different tests, it had no way to ensure
it would get the best fitting at the best price for a given application.
The Navy needed a universal test standard.
The Navy had a choice; it could write a military product specification(s)
for one or more of the already approved MAF types or it could
write a universal performance standard for testing that would
apply to all current and future MAF products. By selecting and
specifying a preferred MAF technology, the Navy could end the
testing controversy and be assured of an acceptable MAF solution
to its pipe fitting requirements.
Developing a universal test standard would be a more difficult
task because it would need to address all of the differing MAF
technologies and would require reaching consensus on acceptable
test procedures among all the MAF manufacturers.
Developing new military specifications for MAFs, while offering
an easier solution, had the potential of limiting competition,
proliferating military documents, and possibly discouraging innovation.
The Navys MAF life-cycle manager chose to work with industry
to develop a nongovernment performance standard for MAF testing,
an approach advocated by the industry. This approach prevailed
because increasing competition, stimulating innovation, and helping
drive down unit costs outweighed the added effort to reach consensus
on an NGS.
The life-cycle manager led the effort to develop a single non-government
MAF test standard. He worked with industry to accelerate NGS development
and to speed adoption of this important new technology.
An NGS subcommittee with jurisdiction over MAFs already existed
within ASTM (F25.13 on Piping Systems, part of Committee F25 on Shipbuilding), but it had been relatively inactive. The Navy,
working with its industry partners, revitalized the committee
to reach consensus on a common standard.
Committee members included the key MAF manufacturers with the
U.S. Coast Guard and the Navy representing the user community.
The Navy conducted aggressive market research to evaluate the
range and capabilities of available products and worked diligently
to evaluate, approve, and track MAF designs for Navy applications.
The goal was to produce a standard acceptable to the Navy and
build industry consensus on testing. The result was a flexible
but stringent commercial performance standard, ASTM Standard F 1387, Specification for Performance of Mechanically Attached Fittings,
which addressed all potential MAF designs. These efforts enabled
the Navy to adopt and use many MAF designs early and successfully
with substantial savings. By 1993, the Navy had used many approved
MAFs with excellent results and saved millions of dollars in the
first few years.
One-Time Investment Cost
The ASTM standard F 1387 development took three years and resulted
in a single ASTM standard plus a supplement for certain unique
Navy requirements. The Navy representative devoted about half
his time during this period to conducting market research, evaluating
tests, coordinating with interested parties, and expediting the
Other government employees were involved to a lesser degree, including
the U.S. Coast Guard committee member and various Navy engineers
who coordinated on technical issues such as pipe structural strength
and fire-related requirements. Table 1 shows the one-time investments costs.
The participating MAF manufacturers each brought their own test
procedures and requirements to the committee for consideration.
The Navy had a consultant perform a study of commercial pipe-joint
testing practices, procedures, and requirements used in the United
States and overseas. This study established a baseline and helped
the committee develop a complete and robust standard. The Navy
also funded a study by the Massachusetts Institute of Technology
(MIT) to determine the minimum number of MAF design types, quantities,
and sizes that must be tested to approve or qualify a manufacturers
family of MAFs for Navy use.
Developing an NGS performance standard rather than a military
product specification increased competition in MAFs, which resulted
in more stock numbers in the Navy system. A military specification
might have resulted in about 100 different stock numbers. The
ASTM performance-based standard motivated manufacturers to produce
additional new products to meet the requirements, resulting in
about four times more stock numbers in the system. Maintaining
a stock number takes an estimated $100 per year. Developing a
military specification would have cost $10,000 per year to maintain
100 stock numbers, while the NGS approach costs about $40,000
per year to maintain 400 stock numbers; a $30,000 difference in
annual recurring cost, or $300,000 during a 10-year period.
It also costs the Navy two to three person-weeks per year to maintain
a document, whether it is military or NGS. A military specification
must be kept current and periodically validated. An adopted NGS
also must be maintained, and the Navys cost is incurred through
its participation in the NGS consensus process. For MAFs, the
costs of maintenance for a military specification or NGS are considered
equal. Table 2 shows a comparison of recurring costs between an NGS and a military
One-Time Cost Savings
During the development of ASTM Standard F 1387, the manufacturers
funded and conducted about $1 million worth of MAF testing to
prove concepts and validate tests. The Navy would have needed
to fund similar tests if it had chosen to develop a military specification.
The NGS route resulted in considerable savings for the Navy.
Each MAF requires six to 12 months to complete qualification testing.
By expediting the development of the ASTM standard and engaging
industry in validation, the Navy brought the new technology to
the fleet faster, better, cheaper, and with greater choice of
products. Savings were available to the Navy an estimated three
years earlier through development of an NGS rather than a military
standard. The Navy was able to leverage the industry resources
rather than conducting the research, testing, and validating using
its own resources. Table 3 shows the Navys one-time cost savings of an NGS.
Recurring Cost Savings
Several different cost studies show that the use of MAFs saves
up to 50 percent of the installed cost compared with the use of
welded or brazed fittings. Table 4 shows that the actual savings per installed unit vary significantly,
depending on the type of system, the fitting, labor rates, and
other factors. Although the material cost of an MAF is higher
than the same configuration welded fitting, the labor cost savings
more than offset the increased material cost, resulting in a lower
total installed cost.
About a third of the Navys approximately 300 ships spend time
in repair or overhaul each year. The Navy installs an estimated
2,500 MAFs per year on these ships using Ship Intermediate Maintenance
Activity (SIMA) or ships crew. In addition, shipyards install
an estimated 40,000 MAFs each year in ship overhauls and new ship
Table 5 shows an average recurring cost savings with NGSs rather than
Table 6 shows one-time and recurring costs and savings using NGSs rather
than military standards.
New, emerging, and changing technologies are important opportunities
for performance-based standardization. Using performance-based
NGS may provide better results than developing and using military
specifications. Standardization can yield dramatic resultssimple
items, such as pipe fittings, can provide opportunities for huge
savings. Individual initiatives in standardization can make major
differences. As the Navy continues to qualify new MAFs and adds
new applications for MAFs, the recurring savings and cost avoidance
continues to grow. //
Copyright 2001, ASTM