| Forewarning
of 4 1/2" Thread Change - Effective
January 1, 2001
Star Fiber Glass
Systems - San Antonio, TX will change the length of our 4 1/2 8RD thread to more
closely conform with API Standard 5B, Specification for
Threading, Gauging and Thread Inspection of Casing, Tubing and
Line Pipe Threads, Table 14 - "External-Upset Long
Round Thread Dimensions for Fiberglass Pipe". Old
thread length / New thread length (4 1/2" / 3 3/4")
As you may be aware,
our current 4 1/2" female threads are incompatible in the industry.
They are 1/2" longer on the big side which result in
standard pins locking up at the vanishing plane before full engagement
can be achieved. This extra length is allowed in API STD
15HR and 15 years ago we choose to utilize it. However,
any advantages of these extra thread, if any, have not been
worth compatibility issues. Technology, testing and
hindsight have shown us this.
What to expect in
the field:
Old Star Pin in New
Box: No Problem. You will see 6 Threads showing,
but full engagement is obtained.
New Pin in Old Star
Box: NOT RECOMMENDED. At make up position, the old box swallows the new
pin by 2 threads (rather than normal 2 threads showing).
This leaves one turn before running out of threads. Star
plans to implement the new thread on all pipe, fittings and
accessories as of January 2, 2002. Of course, Star will
offer cross over fittings (new to old) as necessary. All
products manufactured with the new thread will be marked with BLUE
PAINT for a minimum of 6 months or until the transition is
complete. |