Nipo Flange
Nipoflange is a connection that has a flange on one side and a Nipolet on the other side.
ASME B16.5 is the standard specification for pipe flanges and flanged fittings sized from NPS 1/2 (DN 15) to NPS 24 (DN 600). It is the most widely used flange standard in piping industry. This standard is developed by the sectional Committee B16 of Americal Standards Association (ASA). It is derived from the 1932 revision of ASA B16E. During its development history, the standard had been published as ASA B16.5, ANSI B16.5, ASME/ ANSI B16.5. Then, on October 3, 1996, it was approved with the new formal designation ASME B16.5. So far, we have several editions of ASME B16.9: 2003, 2009, and 2013.
ASME B16.5 standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing, and methods of designating openings for pipe flange and flanged fittings. ASME B16.5 standard covers Steel Pipe Flanges and Flanged Fittings from NPS 1/2 through NPS 24 Metric/Inch in pressure class 150 to class 2500.
ASME B16.5 limited to:
Flanges with rating class of 150#, 300#, 400#, 600#, 900# and 1500# in sizes NPS 1/2 to 24. For 2500# in sizes from NPS 1/2 to NPS 12, with requirements in both metric and U.S. Customary units with diameter of bolts and flange bolt holes expressed in inch units.
Flanged fittings with 150#, 300# in sizes of NPS 1/2 to NPS 24, expressed in inch Units.
Flanged fittings with 400#, 600#, 900#, and 1500# from NPS 1/2 to NPS24, and 2500# from NPS 1/2 to NPS 12, which only US. Customary units are provided. More details visit Nonmandatory Appendix E in ASME B16.5.
Class, followed by a dimensionless number, is the designation for pressure-temperaure ratings as follows:
Class 150 300 400 600 900 1500 2500
In NPS, is designation for nominal flange or flange fittings size. NPS related to nominal diameter, DN in international standards, relations as below:
NPS |
DN |
1/2 |
15 |
3/4 |
20 |
1 |
25 |
1 1/4 |
32 |
1 1/2 |
40 |
2 |
50 |
2 1/2 |
65 |
3 |
80 |
4 |
100 |
Note: For NPS ≥ 4, the related DN = 25 multiplied by the NPS number. For example NPS 10 is DN250.
The pressure-temperature rating is the maximum allowable working pressure (bar unit) of the material and grade used at the rated temperature (Celsius).
A flanged joint is composed of separate and independent, although interrelated components: the flanges, gasket, and bolting, which are assembled by another influence, the assembler. Proper controls must be exercised in the selection and application for all these elements to attain a joint that has acceptable leak tightness. Special techniques, such as controlled bolt tightening, are described in ASME PCC-1
If the flanges of a flange joint have different pressure-temperature ratings, the flange joint shall be rated for the lower of the two ratings at that temperature at any temperature.
The rated temperature corresponding to the rated pressure is refers to the temperature of the pressure vessel of the flange and flange fittings. This temperature is generally the same as the temperature of the stored liquid.
Use of a pressure rating corresponding to a temperature other than that of the contained fluid is the responsibility of the user, subject to the requirements of applicable codes and regulations. For any temperature below−29°C (−20°F),the rating shall be no greater than the rating shown for −29°C(−20°F).
Whether flange joints are used at high or low temperatures, leakage due to external forces and moments generated by the connected piping or equipment should be considered. To prevent leakage, pipe flanges and flanged fittings should avoid the application of severe external loads and sharp thermal gradients.
Application at temperatures in the creep range will result in decreasing bolt loads as relaxation of flanges, bolts, and gaskets takes place. Flanged joints subjected to thermal gradients may likewise be subject to decreasing bolt loads. Decreased bolt loads diminish the capacity of the flanged joint to sustain loads effectively without leakage. At temperatures above 200°C (400°F) for Class 150 and above 400°C (750°F) for other class designations, flanged joints may develop leakage problems unless care is taken to avoid imposing severe external loads, severe thermal gradients, or both.
Some materials, especially some carbon steel materials, exhibit a significant decrease in ductility when used at low temperatures, and thus cannot withstand impact load, sudden stress changes, and high stress concentrations. Some regulations require an impact test even when the temperature is above -29 °C (−20°F).
Flanged joints and flanged fittings may be subjected to system hydrostatic tests at a pressure of 1.5 times the 38°C (100°F) rating rounded off to the next higher 1 bar (25 psi)
increment. Testing at any higher pressure is the responsibility of the user,taking into account the requirements of the applicable code or regulation.
A ASME B16.5 flange shall furnished with below marking requirements. Flange and flange fittings shall be marked in accordance with MSS SP-25 except for modifications to this specification.
Material required for flanges and flanged fittings commonly are:
Notes:
(1) Plate and flat bar materials shall be used only for blind flanges and reducing flanges without hubs.
(2) Flanges and flanged fittings shall be manufactured as one piece in accordance with the applicable material specification. Assembly of multiple pieces into the finished product by welding or other means is not permitted by this Standard
The mechanical properties shall be determined from the specimen and the specimen shall represent the final heat treated condition of the material as required by the material standard.
Include high strength bolts, medium strength bolts, low strength bolts and bolts for grey cast iron flanges.
The material of the ring gasket shall comply with ASME B 16.20. The user is responsible for selecting gasket materials that are suitable for operating conditions, can withstand bolt loads, and do not cause cracking.
ASME B16.5 flange dimensions including different pressure ratings for weld neck flange, slip on flange, blind flange, reducing flange, socket weld flange, threaded flange, view below for more details.
In order to determine compliance with this standard, where a fixed effective number is required where the limits, maximum and minimum values are specified, rounding shall be in accordance with the method defined in ASTM Practice E29.
Required tolerances for different flanges and flanged fittings elements are as follows:
(a). Center-to-Contract Surfaces other than Ring Joint
Size |
Tolerance |
NPS ≤ 10 |
+/- 1.0 mm (+/- 0.03 in.) |
NPS ≤ 12 |
+/- 1.5 mm (+/- 0.06 in.) |
(b). Center-to-End (Ring Joint)
Size |
Tolerance |
NPS ≤ 10 |
+/- 1.0 mm (+/- 0.03 in.) |
NPS ≤ 12 |
+/- 1.5 mm (+/- 0.06 in.) |
(c). Center surface-to-Contact surface other than ring joint
Size |
Tolerance |
NPS ≤ 10 |
±2.0 mm(±0.06 in.) |
NPS ≥ 12 |
±3.0 mm(±0.12 in.) |
(d). End-to-End
Size |
Tolerance |
NPS ≤ 10 |
±2.0 mm(±0.06 in.) |
NPS ≥ 12 |
±3.0 mm(±0.12 in.) |
For both flange and flanged fittings facings tolerances are as follows:
(a) Inside and outside diameter of large and small tongue and groove and female, ±0.5 mm (±0.02 in.).
(b) Outside diameter,2.0 mm (0.06 in.) raised face, ±1.0 mm (±0.03 in.).
(c) Outside diameter, 7.0 mm (0.25 in.) raised face, ±0.5 mm (±0.02 in.).
(d) Ring joint groove tolerances are shown in Table 5 (Table II-5 of Mandatory Appendix II in ASME B16.5)
(e)Perpendicularity of the face with the bore as below table
Size |
Tolerance |
NPS ≤ 5 |
1 deg |
NPS ≥ 6 |
0.5 deg |
Size |
Tolerance |
NPS ≤ 18 |
+3.0, -0.0 mm (+0.12,-0.00 in.) |
NPS ≥ 20 |
+5.0, -0.0 mm (+0.19,-0.00 in.) |
The plus tolerance is applicable to bolting bearing surfaces whether as-forged, as-cast, spot-faced, or back-faced.
For welding ends of welding neck flanges nominal outside diameter as follows:
Size |
Tolerance |
NPS ≤ 5 |
+2.0, -1.0 mm (+0.09,-0.03 in.) |
NPS ≥ 6 |
+4.0, -1.0 mm (+0.16,-0.03 in.) |
Tolerances for nominal inside diameter of welding ends of weld neck flange and socket weld flange with smaller bore.
(a) For figures 7 (Bevel for wall thickness from 5 mm to 22 mm), figure 8 (greater than 22 mm) and figure 4 (Straight Hub Welding Flange) in ASME B16.5.
Size |
Tolerance |
NPS ≤ 10 |
±1.0 mm (±0.03 in.) |
12 ≤ NPS ≤ 18 |
±1.5 mm (±0.06 in.) |
NPS ≥ 20 |
+3.0, -1.5 mm (+0.12,-0.06 in.) |
For figure 9 (Inside Contour for Use With Rectangular Backing Ring)
Size |
Tolerance |
NPS ≤ 10 |
+0.0, -1.0 mm (+0.0,-0.03 in.) |
NPS ≥ 12 |
+0.0, -1.5 mm (+0.0,-0.06 in.) |
Size |
Tolerance |
2 ≤ NPS ≤ 24 |
+0.25, -0.0 mm (+0.01,-0.0 in.) |
Size |
Tolerance |
NPS ≤ 4 |
±1.5mm (±0.06 in.) |
5 ≤ NPS ≤ 10 |
+1.5, -3.0 mm (+0.06,-0.12 in.) |
NPS ≥ 12 |
+3.0, -5 mm (+0.12,-0.18 in.) |
Size |
Tolerance |
NPS ≤ 10 |
+1.0, -0.0 mm (+0.03,-0.0 in.) |
NPS ≥ 12 |
+1.5, -0.0 mm (+0.06,-0.0 in.) |
Size |
Tolerance |
NPS ≤ 10 |
+1.0, -0.0 mm (+0.03,-0.0 in.) |
NPS ≥ 12 |
+1.5, -0.0 mm (+0.06,-0.0 in.) |
Size |
Tolerance |
1/2 ≤ NPS ≤ 3 |
±0.25 mm (±0.010 in.) |
No pressure test is required on the flange.
Flanged fitting should be tested for shell pressure.
The shell pressure test for flanged fittings shall be at a pressure no less than 1.5 times the 38°C (100°F) pressure rating rounded off to the next higher 1 bar (25 psi) increment.
The shell pressure test for flanged fittings shall be at a pressure no less than 1.5 times the 38°C (100°F) pressure rating rounded off to the next higher 1 bar (25 psi) increment
Flanged Fittings Size |
Duration, Sec |
NPS ≤ 2 |
60 |
2 1/2 ≤ NPS ≤ 8 |
120 |
NPS ≥ 10 |
180 |