1.1 GENERAL
2.1 PARTIAL COMPLIANCE FITTINGS
2.2 FABRICATED FITTINGS
3. DEFINITIONS
The allowable pressure ratings for fittings designed in accordance with this Standard
Practice may be calculated as for straight seamless pipe in accordance with the rules
established in the applicable sections of ANSI/ASME B31, Code for Pressure Piping.
The pipe wall thickness and material type shall be that with which
the fittings have been ordered to be used; their identity on the fittings is in
lieu of pressure rating markings. The pipe fitting manufacturer certifies that his
pipe fitting complies with this Standard Practice when his
name or trademark is marked on the body of the fitting.
This Standard covers 1/4 through 12 NPS stainless steel and copper-nickel belled end
socket welding fittings
including dimensions, tolerances, materials, socket end preparation for welding, heat
treating and market
requirements for use with the following pipe standards.
2. SPECIAL CONSIDERATIONS
Fittings may be made to special dimensions, sizes, shapes, tolerances, or of wrought
materials other than those covered by this Standard Practice by agreement between the
manufacturer and the purchaser. When such fittings meet all other stipulations of this
Standard Practice, they shau be considered as being in partial compliance
therewith, provided as they are appropriately marked.
Fabricated laterals and fittingss employing intersecting welds are considered pipe
fabrications and shall be manufactured in accordance with ANSI/ASME B31, Code for Pressure
Piping.
4. PRESSURE RATINGS
6. SIZE
The sizes of fittings, excepting only short radius elbows and thermometer well tees
shall be from 1/4 NPS through 12 NPS. Short radius elbows shall be from 1 NPS through
12 NPS. Thermometer well tees shall have a body size of no larger than 2 NPS.
As an initiative to reduce the numbers of combinations of reducing tees, the
following sizing format is established:
Stainless steel fittings except caps shall be made from stainless steel pipe,
ASTM Designation A 312, of a material grade listed in Table 1 therein or
from stainless steel sheet to ASTM Designation A 240. Caps, all sizes, shall be
made from stainless steel sheet to ASTM Designation A 240.
Copper nickel fittings except caps shall be made from copper nickel pipe,
either Military Specification MIL-T-16420, Type I (seamless), of a material
composition allowed by paragraph 1.2 therein or ASTM Designation B 466 or B 467 of an
alloy listed in Table I therein or from copper nickel sheet to either MIL-C-15726 or
ASTM Designation B 122. Caps, all sizes, shall be made from copper nickel
sheet to either MIL-C-15726 or ASTM Designation B 122.
8. FORMING AND FABRICATING
Whenever practicable, fittings shall be formed in one piece from pipe or sheet.
Fittings may be fabricated from ASME/ANSI B 16.9 wrought fittings on to which a
tangent end has been welded. The length of the tangent end shall be equal to the
socket depth plus the transition length. The tangent end may be belled either
before or after attachment.
Thermometer well tees utilizing extruded branch connections shall be fabricated in
accordance with ASME B31.1 requirements for extruded outlets, integrally reinforced.
The radius of curvature of the external contoured portion of the branch outlet measured
in the plane containing the axes of the run and the branch shall
not be less than 0.05 times the outside diameter of the branch.
The nominal pipe size of the bodies of these fittings shall not exceed 2 NPS.
Fittings fabricated from mirror image halves which are longitudinally welded
shall have the interior and
exterior crowns of the longitudinal welds ground flush for a distance of the socket
and the transition prior to the belling operation in order that the socket wall
will expand uniformly.
The following requirements pertain to all fitting fabrication welds:
9. FITTING DIMENSIONS
Dimensions for fittings and sockets are given in Tables 2 through 13.
10. TOLERANCES
Dimensional tolerances are given in Table 1.
The socket end face shall be flat and of a height no less than the minimum wall
thickness for the pipe with which the fitting identifies. The socket end face serves
as a guide for fillet weld height.
The choice of materials and/or the forrning process may produce a heavy socket
wall thickness. When the socket wall thickness will result in a weld height of
more than 150% of the minimum, a 15 degree chamfer
shall be made on the OD of the socket wall to reduce the weld
preparation height to within limits.
12. JOINT FILLET WELD
The height of the joint fillet weld shall equal the fitting socket face height and
shall extend 1.75 times that distance along the length of the pipe.
The slope of the weld face when measured from the horizontal (pipe sur-
face) shall not exceed 30 degrees.
13. FINISH
Fittings supplied under this Standard Practice shall be examined visually.
Surface discontinuities shall be explored for depth.
Surface discontinuities deeper than 5% of the minimum wall thickness or surface checks
(fish scale) deeper than 1/64 inch (0.4 mm) or mechanical marks deeper than
1/16 inch (1.6 mm) shall be
removed by machining or grinding to sound metal and the repaired areas shall be well
faired. The welding repair of cracks or of any surface discontinuities is not allowable.
The reconstitution of minimum wall thickness by welding is not allowable.
The removal of a weid discontinuity and re-welding is part of the welding
process and is allowable if done before final heat treatment.
Dents may be re-formed. When the removal of a surface discontinuity reduces the wall
thickness below the minimum wall limits, the fitting shall be rejected.
Surfaces shall be free of black oxide and have roughness values not exceeding
125 RMS.
14. HEAT TREATMENT
All welding must be done prior to the final heat treatment.
Copper nickel fittings: All fittin2s shall be furnished in the fully annealed condition.
Annealing, shall be performed at 1300 +/- 50 F per hour per inch of thickness.
Cooling shall be effected in still air.
Annealing shall not reduce the material below minimum mechanical strength requirements.
15. MARKING
All fittings shall be permanently marked by electro-etch or engraving pencil.
The electrolyte shall not contain harmful amounts of chlorides, metals or metallic
salts, such as zinc or copper, that would cause corrosive attack on heating.
No metal impression stamps shall be used.
All fittings shall be marked with the prescribed information in accordance with MSS SP-25.
The prescribed information shall be as follows:
In those cases where the size of the fitting will not pennit the complete
marking, the size of the marking
may be reduced. If complete marking is not possible, then lines of identification
may be omitted in the following order.
E-mail
fittings@bestweld.com
7. MATERIALS
Each fitting shall be heat treated after completion irrespective of forming or
fabrication process.
Hydrostatic testing is not required. All fittings shall be capable of
withstanding a hydrostatic test pressure
of the pipe with which they identify without leakage and without
impairing their serviceability.
Distances shown in the fitting sketches from the center of fittings to a pipe
piece are pipe fabrication assembly design dimensions, thus are not assigned
fitting manufacturing tolerances.
Squareness, vis., off angle and off plane, tolerances are the same values and are as
follows:
NPS range
1/4 to 1 1/2
2 to 6
8 to 12
VIZ Tolerance, inches
1/16
1/8
3/16
Stainless steel fittings: All fittings shall be fumished in the heat-treated condition.
The heat-treat procedure,
except for those grades listed below, shall consist of solution annealing the
fittings at a minimum temperature of
1900 degrees F (1040 degrees C) until the chromium carbides go into solution,
and then cooling at a sufficient
rate to prevent re-precipitation. Grades 321H, 347H and 348H shall be solution
annealed at 1925 degrees F (1050 degrees C minimum).
S31254 shall be solution annealed at 2100 degrees F (1150 degrees C) minimum.
S33228 shall be solution annealed at 2050 degrees F (1120 degrees C) minimum.
S34565 shall be solution annealed in the range of 2050 degrees F (1120 delrees C)
to 2140 degrees F (1170 degrees C). The maximum temperature for
solution annealing grades 321, 321H, 347 and 347H shall be 2100 degrees F (1150 degrees C).
The Method of Manufacture shall be described by the following symbols:
The following are examples of fitting markings:
(A stainless steel fitting) (A copper nickel fitting)
Manufacturer Manufacturer
6 NPS SIO 6 NPS Class 200
WP 304L-W WP 90/1 O-S CU-N]
MSS-SP-TBD MSS-SP-TBD
MFR-PROD # MFR. PROD #
07/04/95 07/04/95
Stainless steel fittings meeting the chemical and mechanical property
requirements of Tables 1 and 2 of
ASTM Designation A312 for more than one class or gtade may be marked with
more than one class or grade
designation, such as WP304/304L or WP304/304L/304N or WP304/304H, etc.