Open Discussion on Fittings Used in Subsea Applications

1
Open Discussion on Fittings Used in Subsea
Applications Standards and Future Challenges

• COIN Soap Box Meeting 4 (SBM4)
• Presented by Mark Holder

2
Fittings Considerations for Subsea Equipment

• There are many considerations to keep in mind
  when determining which fitting to use. Questions
  to keep in mind in the determination are as
  follows
• Is the fitting exposed to ambient sea water
  conditions or dielectric service such as in a
  SCM?
• Is the maximum operating temperature at or
  below 140F?
• Is the fitting tied into the cathodic
  protection system?
• Is the service condition driven by NACE
  MR0175/ISO 15156 (exposed or potentially exposed
  to wellbore condition)?
• Is the fitting required to be rated to the RWP
  of the tree?

3
Other Considerations

• There are other considerations that must be
  evaluated in the selection of fittings. These
  include
• Are there customer expectations for the
  fittings such as test ports verifying the makeup?
  (example tubing hanger fittings)
• Are there fitting requirements defined within
  the customer specification such as anti
  back-off , anti vibration or metal to metal?
• If a fitting is specified by the customer, is
  it qualified and to what requirements? (PTI, Well
  Dynamics, Butech, Nova, Production Quest, etc)
• Do the other items in the circuit have
  consistent ports or connections? (Hot stab
  receptacles, needle valves, etc)
• Are there interface requirements/constraints
  which may prohibit a fitting?
• Are there standard practices in installation
  that have been defined and accepted?
• What tubing is to be used to interface the
  fitting (tube material, hardness, etc)?

4
Which Fitting?

• With all of the fitting manufacturers and types
  of fittings and interfaces availablehow do we
  chose the best fitting for the application?
• We need to look at the fittings with their pros
  and cons, review the application to determine
  the requirement of the fitting, what fittings
  have been qualified to meet the applications,
  field and rework considerations, etc.
• This is not an easy task!

5
Common Problems To Fittings

• Fittings have common problems that we must
  evaluate. These problems include
• Proper make-up and installation customers are
  specifying welded connections more frequently as
  the techniques used to inspect mechanically
  attached fittings is lacking. There appears to
  be a lack of trust in how fittings are installed.
• Lack of adequate length of tube insertion into
  compression style fittings
• Under or over tightened causing the tube to
  slip or threaded connections to back off
• Cone and threaded fittings have inherent issues
• Taper must be machined properly (angle and
  surface finish)
• Alignment of the tube cone to the sealing cone
  may be difficult with heavier walled tubes
• Anti vibration fittings must be used as the
  standard gland fittings are poor when it comes to
  vibration resistance
• These fittings are labor intensive in the cone
  and thread operation and make up
• Proper lubricants must be used or the torque
  values specified are invalid
• Potential for galled threads with some material
  combinations

6
Requirements of Fittings

• How are fittings qualified and what as an
  industry should we use as a standard?
• There are a couple of good standards that can
  certainly apply to the qualification of a
  fitting. Two such standards are ASTM F1387 and
  ISO 19879. FMCTI has standardized on the ASTM
  standard as it covers all of the tests identified
  within the ISO document but also includes other
  important tests.
• FMCTI has also performed a review of the fittings
  materials of construction and identified what the
  material should be as a standard based on service
  conditions. These service conditions take into
  account the circuit (Control Line service,
  Chemical Injection Service, Test Line Service,
  Tubing Hanger Service) as well as the
  considerations presented earlier.
• Taking all of this into accountwhat do we have?

7
FMCTI Standard Fittings

• For lower pressure circuits such as for control
  line interface to valves, compensation circuits,
  hot stab interface for lock and unlock of
  connectors, etc limited to the control system
  working pressure of 3,000 to 5,000-PSI (207 to
  345 bar) the 37 degree SAE J514 metal to metal
  sealing JIC interface was selected as the
  standard threaded port and the twin ferrule
  compression fittings were selected for tube
  interface.
• For higher pressure circuits such as for test
  lines, the medium pressure or high pressure cone
  and thread interface was selected as it too is a
  metal to metal sealing fitting.
• The requirement for standard fittings is for
  subsea ambient temps and exposure, tied in the CP
  system and has no potential for exposure to
  production or annular fluids or NACE/ISO
  requirement.
• Some equipment does not however have these
  connections as a standard which introduces
  difficultywe have to adapt.

8
Proper Use and Installation

• FMCTI recognizes the issues facing everyone with
  regards to fittings. As a result, FMCTI has
  contacted the fitting manufacturers and captured
  their recommended practices for installation,
  their qualification records or statements, the
  OEM catalog of fittings accepted within FMCTI,
  the pressure ratings of the connections present
  for the fittings all in an effort to ensure the
  fittings are used properly and are installed
  correctly.
• What about the other fittings (which we will call
  specialty fittings)?

9
FMCTI Specialty Fittings

• Specialty fittings are those that are exposed to
  elevated temperatures, have the potential for
  exposure to production or annular fluids, or are
  installed in systems that lack cathodic
  protection, etc. These fittings typically have
  material of construction changes required to meet
  the service conditions.
• These fittings require greater scrutiny, for
  example those used in tubing hangers. Materials
  of construction review is required for
  temperature and/or level of exposure. Service
  conditions define the level of qualification
  required to ensure the fitting meets design life
  criteria. Accessibility and installation may
  also pose a problem if a condition should arise
  in testing.

10
Specialty Fittings

• Specialty fittings can be as simple as an alloy
  625 compression fitting (for elevated temperature
  or lack of CP) or as complex as a fitting used in
  a tubing hanger with test ports and multiple
  seals.
• Tubing hanger fittings pose some interesting
  challenges. The fitting materials are required
  to be NACE/ISO compliant which typically are
  lower hardness materials but are required to bite
  or seal on tubing. The preferred method of
  interface to the tube is via swaging as it is
  quick and simple. The issue is twofold. The
  tube has to be NACE/ISO compliant, have thin
  enough wall to be swaged and yet thick enough to
  maintain the pressure. In most cases, this means
  the tubing used does not maintain the same safety
  factors applied to the industry tubes such as
  ASME B31.3 (41) and/or reaching the hardness
  limits with higher strength materials. The
  ferrules used to bite on the tubes are meant to
  be higher in hardness to ensure the ferrules bite
  into the tubes and do not deform around the tube
  but again may be limited due to NACE/ISO.

11
Specialty Fittings cont.

• Not to be negative, but to open the discussion
• The ferrules used by companies manufacturing
  tubing hanger fittings in most cases are not of
  their design but of companies such as Swagelok.
  This means they are manufacturing a fitting body
  and using another companies ferrules. Swagelok
  does not condone using their ferrules nor do they
  warrant to the pressures indicated indicating
  that the pressure rating limit is to the ASME
  B31.3 rating of the tube. Discussions with
  Parker and Swagelok in development of these
  fittings have not so far been very productive.
• This requires the fittings manufacturers to fully
  warrant their products inclusive of other
  companies components. When you ask these same
  companies how they have qualified their fitting
  designs, you get mixed results. Remember, these
  companies did not establish the original ferrule
  to body design and have re-engineered the
  interface.
• What do we do?

12
Future Challenges

• Fittings and fitting interfaces are reaching a
  critical point. We as an industry have yet to
  define a fitting that everyone is comfortable
  with either in performance or in installation.
  This applies to both low and higher pressure
  applications. Because we have reached this point
  with limited solutions, some customers have
  imposed welding as a solution using RT as a
  criteria with which to grade the weld. This may
  not be possible for tubing hanger interface.
  Field maintenance and repair then becomes a
  challenge potentially requiring re-weld and NDE
  in environments that do not support or allow
  these activities
• For 20K applicationswhere do we go from here?
  Do we use cone and thread HP connections? Will
  the tubing support this downhole?

13
Potential Solutions

• FMCTI has been evaluating different fittings and
  connection methods in an effort to not only meet
  requirements but to provide a solution that is
  efficient and easy to install, has a way to
  measure the installation to ensure it has been
  assembled properly and is robust to meet the
  future demands.
• The SAE J518 code 62 4-bolt flange is being
  investigated for the lower pressure (6KSI or
  less) circuits such as for control and
  compensation circuits. The code 62 flange has an
  extensive history on heavy machinery and is
  extremely rugged in design. Incorporation of a
  metallic seal would alleviate any concerns for
  elevated temperatures or other issues in the use
  of elastomers if needed. It requires torque of 4
  bolts which can be measured, not questioning the
  tube interface as it can be welded.
• There are still challenges with OEM providers
  meeting this interface

14
Potential Solutions cont.

• For higher pressure applications, FMCTI is
  evaluating permanent solutions which are not
  defined as welded. These permanent solutions
  could be shaped memory alloys, swaging fittings
  such as Parkers Phastite and Tube-Macs
  Pyplokor other fittings as they are being
  developed. All fittings reviewed to date have
  pros and cons which is why a clear winner
  hasnt been established. We may be in a
  situation where we need to determine what the
  market is willing to tolerate in light of the
  current problems we face with fittings. There
  may not be a perfect fitting out there for every
  applications which means
• What are we willing to accept?

15
Open Discussion

• Can we drive establishing a standard in
  interfaces similar to what ISO 13628-8/API 17H is
  doing with ROV tooling?
• What performance criteria do we establish or
  accept as a standard in evaluating a fittings
  performance?
• How do we better communicate or relay information
  with regards to fittings across the industry so
  we all benefit from the experiences?
• Have painful or costly experiences driven the
  market to define the requirements we see in
  specifications today or is it a case of a
  consultant or consulting group making their
  recommendations to better leverage their
  position?
• IDEAS?