MSS SP 97 Weldolet ASTM A105,A105N Weldolet

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MSS SP-97 ASTM A105 / A105N Weldolet & Threadolet | Socket Weld Branch Outlet Fittings NACE MR0175

We are a professional manufacturer and exporter of ASTM A105  Weldolet, A105N Weldolet, A105 Threadolet, and Socket Weld Olet in China, providing integrally reinforced forged branch outlet fittings for petroleum, chemical, power, shipbuilding, and industrial applications worldwide.

What is a Weldolet / Threadolet?

  • Weldolet: A branch connection with a butt-weld end used to create a reinforced lateral connection on a pressure pipe.
  • Threadolet: A threaded branch outlet allowing connection without welding.
  • Socket Weld Olet: A socket-welded branch outlet providing strong, leak-proof connections.

These fittings allow branching from main pipelines while maintaining strength and pressure integrity.

Material Standards

Material Type Standard
Carbon Steel ASTM A105, A105N, ASTM A350 LF2
Alloy Steel ASTM A182 F11, F22, F12, F5, F9, F91
Stainless Steel ASTM A182 F304/F304L, F316/F316L, F321/F321H, F347/F347H, S31803 Duplex, S32750 Super Duplex
Line Pipe Compatibility ASTM A694 F42, F46, F52, F56, F60, F65, F70
Special Alloys Monel, Inconel, Alloy 20, Nickel Alloy, 904L

Type & Application

  • Available Types: Weldolet, Threadolet, Socket Weld Olet
  • Sizes: 1/2″ – 60″ (DN15 – DN1500)
  • Wall Thickness: SCH 40 – SCH XXS
  • Pressure Ratings: 2000#, 3000#, 6000#, 9000#
  • Application: Petroleum, chemical, power plants, shipbuilding, nuclear, urban construction, hot-water systems, fire prevention, metallurgy, aerospace.

Standards & Specifications

  • ASME / ANSI: B16.11 – Forged Fittings Socket-Welding and Threaded
  • MSS: SP-97 – Integrally Reinforced Forged Branch Outlet Fittings
  • Material Test Certificates: EN10204 3.1 available

ASTM A105 / A105N Chemical Composition

Element Max / Range
Carbon (C) 0.15% max
Manganese (Mn) 0.6–1.05%
Phosphorus (P) 0.035% max
Sulfur (S) 0.04% max
Silicon (Si) 0.1% min

Mechanical Properties

Property Value
Tensile Strength 485 MPa
Yield Strength 250 MPa
Elongation 30%

Features & Benefits

  • Integrally reinforced branch outlet ensures high-pressure performance
  • Available in carbon steel, alloy steel, stainless steel, and special alloys
  • Suitable for high-temperature and corrosive environments
  • Butt-weld, socket-weld, and threaded connection options
  • Fully tested and certified for industrial and marine applications

How to Order

Example 1: ASTM A105 Weldolet

  • Type: Weldolet, Butt Weld
  • Size: 4″ × 2″
  • Schedule: SCH 80
  • Pressure: 3000#
  • Material: ASTM A105
  • Standard: MSS SP-97 / ASME B16.11
  • Quantity: 50 PCS

Example 2: A105N Threadolet

  • Type: Threadolet, Threaded
  • Size: 2″ × 1/2″
  • Schedule: SCH 40
  • Pressure: 2000#
  • Material: ASTM A105N
  • Standard: MSS SP-97 / ASME B16.11
  • Quantity: 30 PCS

Applications

  • Petroleum & Gas Pipelines: High-pressure branch connections
  • Chemical Industry: Corrosion-resistant lateral piping
  • Power & Energy Plants: High-temperature and pressure piping
  • Shipbuilding & Marine: Reinforced branch outlets for seawater and fuel lines
  • Nuclear & Aerospace: High-integrity, high-strength branch connections

 

MSS SP-97-2019 

Integrally Reinforced Forged Branch Outlet Fittings – Socket Welding, Threaded and Buttwelding Ends

MSS SP-97-2019 includes essential dimensions, finish, tolerances, testing, marking, material, and minimum strength requirements for 90° and 45° integrally reinforced forged branch outlet fittings of buttwelding, socket welding, and threaded types. 

Unless specified otherwise by the manufacturer, conventional integrally reinforced forged branch outlet fittings are intended for the following header by branch combinations: STD × STD, XS × XS, SCH. 160 × SCH 160, XXS × XXS, XS × 3000, SCH 160 × 6000, and XXS × 9000. When the run and branch pipes are of differing or mixed schedules, then the selection of the branch connection shall be determined by contacting the manufacturer. Such selections shall be agreed upon by purchaser and manufacturer at time of order and may involve supplemental marking requirements determined by other standards (e.g., material grade determination, other factors). See Section 1.3. Mixed schedule branch outlet fittings are unique to the design of each system, and thus outside the scope of this Standard Practice. The adequacy of the design for light, intermediate, and heavy wall branch outlet fittings may be established by mathematical analysis as contained in the applicable pressure vessel or piping codes, or by finite element analysis. 

 

Dimensions Size on Size Weldolet STD – MSS SP97
NPS A B C D L
1/2 INCH
MM		 3/4
19.05		 1-3/8
34.93		 15/16
23.81		 5/8
15.88		 1-3/16
30.16
3/4 INCH
MM		 7/8
22.23		 1-5/8
41.28		 1-3/16
30.16		 13/16
20.64		 1-7/16
36.51
1 INCH
MM		 1-1/16
26.99		 2
50.80		 1-7/16
36.51		 1-1/32
26.19		 1-1/16
26.99
1¼ INCH
MM		 1-1/4
31.75		 2-3/8
60.3		 1-3/4
44.45		 1-3/8
34.93		 2-1/16
52.39
1½ INCH
MM		 1-5/16
33.34		 2-7/8
73		 2
50.80		 1-5/8
41.28		 2-1/4
57.15
2 INCH
MM		 1-1/2
38.10		 3-1/2
88.90		 2-9/16
65.09		 2-1/16
52.39		 2-11/16
68.26
2½ INCH
MM		 1-5/8
41.28		 4-1/16
103.19		 3
76.20		 2-7/16
61.91		 3-1/16
77.79
3 INCH
MM		 1-3/4
44.45		 4-13/16
122.24		 3-11/16
93.66		 3-1/16
77.79		 3-1/2
88.90
3½ INCH
MM		 2
50.80		 5-3/8
136.53		 3-7/8
98.43		 3-9/16
90.49		 3-7/8
98.43
4 INCH
MM		 2
50.80		 6
152.40		 4-3/4
120.65		 4
101.60		 4-1/4
107.95
5 INCH
MM		 2-1/4
57.15		 7-1/8
180.98		 5-9/16
141.29		 5-1/16
128.59		 5-1/16
128.59
6 INCH
MM		 2-3/8
60.3		 8-1/2
215.90		 6-11/16
169.86		 6-1/16
153.99		 5-11/16
144.46
8 INCH
MM		 2-3/4
69.85		 10-3/8
263.53		 8-11/16
220.66		 7-15/16
201.61		 7-1/16
179.39
10 INCH
MM		 3-1/16
77.79		 12-9/16
319.09		 10-13/16
274.64		 10
254.00		 8-7/16
214.31
12 INCH
MM		 3-3/8
85.73		 14-7/8
377.83		 12-13/16
325.44		 12
304.80		 9-3/4
247.65
14 INCH
MM		 3-1/2
88.90		 16-1/8
409.58		 14-1/16
357.19		 13-1/4
336.55		 10-1/2
266.70
16 INCH
MM		 3-11/16
93.66		 18-1/4
463.55		 16-1/16
407.99		 15-1/4
387.35		 11-11/16
296.86
18 INCH
MM		 4-1/16
103.19		 20-3/4
527.05		 18-5/8
473.08		 17-1/4
438.15		 13-1/16
331.79
20 INCH
MM		 4-5/8
117.48		 23-1/16
585.79		 20-1/16
509.59		 19-1/4
488.95		 14-5/8
371.48
24 INCH
MM		 5-3/8
136.53		 27-7/8
708.03		 25-1/8
638.18		 23-1/4
590.55		 17-3/8
441.33
NPS A B C D L
Dimensions Weldolet Reducing – STD – MSS SP97

NPS A B C
1/2 INCH
MM		 3/4
19.05		 1-3/8
34.93		 15/16
23.81
3/4 INCH
MM		 7/8
22.23		 1-3/4
44.45		 1-3/16
30.16
1 INCH
MM		 1-1/16
26.99		 2-1/8
53.98		 1-7/16
36.51
1¼ INCH
MM		 1-1/4
31.75		 2-9/16
65.09		 1-3/4
44.45
1½ INCH
MM		 1-5/16
33.34		 2-7/8
73		 2
50.80
2 INCH
MM		 1-1/2
38.10		 3-1/2
88.90		 2-9/16
65.09
2½ INCH
MM		 1-5/8
41.28		 4-1/16
103.19		 3
76.20
3 INCH
MM		 1-3/4
44.45		 4-13/16
122.24		 3-11/16
93.66
3½ INCH
MM		 1-7/8
47.63		 5-5/8
142.88		 4
101.60
4 INCH
MM		 2
50.80		 6
152.40		 4-3/4
120.65
5 INCH
MM		 2-1/4
57.15		 7-1/16
179.39		 5-9/16
141.29
6 INCH
MM		 2-3/8
60.3		 8-1/2
215.90		 6-11/16
169.86
8 INCH
MM		 2-3/4
69.85		 10-3/8
263.53		 8-11/16
220.66
10 INCH
MM		 3-1/16
77.79		 12-11/16
322.26		 10-13/16
274.64
12 INCH
MM		 3-3/8
85.73		 14-7/8
377.83		 12-13/16
325.44
14 INCH
MM		 3-1/2
88.90		 16-1/8
409.58		 14-1/16
357.19
16 INCH
MM		 3-11/16
93.66		 18-1/4
463.55		 16-1/16
407.99
18 INCH
MM		 3-13/16
96.84		 20-1/2
520.70		 18-1/16
458.79
20 INCH
MM		 4
101.60		 22-1/2
571.50		 20
508.00
24 INCH
MM		 4-9/16
115.89		 27-1/8
688.98		 24-3/16
614.36
NPS A B C
Dimensions (L) Center Line of Run Pipe to Face of Weldolet

 

NPS Outlet Sizes STD and XS NPS 1/2 – 4
1/2 3/4 1 11/4 11/2 2 21/2 3 31/2 4
3/4 INCH
MM		 1-1/4
31.75
1 INCH
MM		 1-3/8
34.92		 1-1/2
38.10
1¼ INCH
MM		 1-9/16
39.68		 1-11/16
42.86		 1-7/8
47.62
1½ INCH
MM		 1-11/16
42.86		 1-13/16
46.03		 2
50.80		 2-3/16
55.56
2 INCH
MM		 1-15/16
49.21		 2-1/16
52.38		 2-1/4
57.15		 2-7/16
61.91		 2-1/2
63.50
2½ INCH
MM		 2-3/16
55.56		 2-5/16
58.73		 2-1/2
63.50		 2-11/16
68.26		 2-3/4
69.85		 2-15/16
74.61
3 INCH
MM		 2-1/2
63.5		 2-5/8
66.67		 2-13/16
71.43		 3
76.20		 3-1/16
77.78		 3-1/4
82.55		 3-3/8
85.72
3½ INCH
MM		 2-3/4
69.85		 2-7/8
73.02		 3-1/16
77.78		 3-1/4
82.55		 3-5/16
84.13		 3-1/2
88.9		 3-5/8
92.07		 3-3/4
95.25
4 INCH
MM		 3
76.2		 3-1/8
79.37		 3-5/16
84.13		 3-1/2
88.90		 3-9/16
90.48		 3-3/4
95.25		 3-7/8
98.42		 4
101.60		 4-1/8
104.77
5 INCH
MM		 3-9/16
90.48		 3-11/16
93.66		 3-7/8
98.42		 4-1/16
103.18		 4-1/8
104.77		 4-5/16
109.53		 4-7/16
112.71		 4-9/16
115.88		 4-11/16
119.06		 4-13/16
122.23
6 INCH
MM		 4-1/16
103.18		 4-3/16
106.36		 4-3/8
111.12		 4-9/16
115.88		 4-5/8
117.47		 4-13/16
122.23		 4-15/16
125.41		 5-1/16
128.58		 5-3/16
131.76		 5-5/16
134.93
8 INCH
MM		 5-1/16
128.58		 5-3/16
131.76		 5-3/8
136.52		 5-9/16
141.28		 5-5/8
142.87		 5-13/16
147.63		 5-15/16
150.81		 6-1/16
153.98		 6-3/16
157.16		 6-5/16
160.3
10 INCH
MM		 6-1/8
155.57		 6-1/4
158.75		 6-7/16
163.51		 6-5/8
168.27		 6-11/16
169.86		 6-7/8
174.62		 7
177.8		 7-1/8
180.97		 7-1/4
184.15		 7-3/8
187.32
12 INCH
MM		 7-1/8
180.97		 7-1/4
184.15		 7-7/16
188.91		 7-5/8
193.67		 7-11/16
195.26		 7-7/8
200.02		 8
203.20		 8-1/8
206.37		 8-1/4
209.55		 8-3/8
212.72
14 INCH
MM		 7-3/4
196.85		 7-7/8
200.02		 8-1/16
204.78		 8-1/4
209.55		 8-5/16
211.13		 8-1/2
215.90		 8-5/8
219.07		 8-3/4
222.25		 8-7/8
225.42		 9
228.60
16 INCH
MM		 8-3/4
222.25		 8-7/8
225.42		 9-1/16
230.18		 9-1/4
234.95		 9-5/16
236.53		 9-1/2
241.30		 9-5/8
244.47		 9-3/4
247.65		 9-7/8
250.82		 10
254.00
18 INCH
MM		 9-3/4
247.65		 9-7/8
250.82		 10-1/16
255.58		 10-1/4
260.35		 10-5/16
261.93		 10-1/2
266.70		 10-5/8
269.87		 10-3/4
273		 10-7/8
276.22		 11
279.40
20 INCH
MM		 10-3/4
273		 10-7/8
276.22		 11-1/16
280.98		 11-1/4
285.75		 11-5/16
287.33		 11-1/2
292.10		 11-5/8
295.27		 11-3/4
298.45		 11-7/8
301.62		 12
304.80
24 INCH
MM		 12-3/4
323.9		 12-7/8
327.02		 13-1/16
331.78		 13-1/4
336.55		 13-5/16
338.13		 13-1/2
342.90		 13-5/8
346.07		 13-3/4
349.25		 13-7/8
352.42		 14
355.60
 NPS 1/2 3/4 1 11/4 11/2 2 21/2 3 31/2 4
Outlet Sizes STD and XS NPS 1/2 – 4
Dimensions (L) Center Line of Run Pipe to Face of Weldolet

 

NPS Outlet Size STD NPS 5 – 20
5 6 8 10 12 14 16 18 20
6 INCH
MM		 5-9/16
141.28
8 INCH
MM		 6-9/16
166.68		 6-11/16
169.86
10 INCH
MM		 7-5/8
193.67		 7-3/4
196.85		 8-1/8
206.37
12 INCH
MM		 8-5/8
219.07		 8-3/4
222.25		 9-1/8
231.77		 9-7/16
239.71
14 INCH
MM		 9-1/4
234.95		 9-3/8
238.12		 9-3/4
247.65		 10-1/16
255.58		 10-3/8
263.52
16 INCH
MM		 10-1/4
260.35		 10-3/8
263.52		 10-3/4
273		 11-1/16
280.98		 11-3/8
288.92		 11-1/2
292.10
18 INCH
MM		 11-1/4
285.75		 11-3/8
288.92		 11-3/4
298.45		 12-1/16
306.38		 12-3/8
314.32		 12-1/2
317.50		 12-11/16
322.26
20 INCH
MM		 12-1/4
311.15		 12-3/8
314.32		 12-3/4
323.9		 13-1/16
331.78		 13-3/8
339.72		 13-1/2
342.90		 13-11/16
347.66		 13-13/16
350.83
24 INCH
MM		 14-1/4
361.95		 14-3/8
365.12		 14-3/4
374.65		 15-1/16
382.58		 15-3/8
390.52		 15-1/2
393.70		 15-11/16
398.46		 15-13/16
401.63		 16
406.40
 NPS 5 6 8 10 12 14 16 18 20
Outlet Size STD NPS 5 – 20

General notes:

  • Root Gap – X – “Space” for welding the O’let is raised off the run pipe to establish proper weld gap by placing spacers, e.g. welding rods, under the fitting. This provides a uniform welding gap between the curvature of the run and base of fitting.
  • X = Root Gap not included in L measure.
  • L = Dimensions Center Line of Run Pipe to Face of Weldolet.
  • Bevelled Ends ASME B16.9 and B16.25.

Please send inquiry to bill@cnpipefitting.com

weldolet

How to Order ASTM A105 Weldolet

A complete inquiry should include:

  • Outlet type
  • Run pipe size
  • Branch size
  • Run pipe schedule
  • Branch schedule
  • Material
  • Quantity
  • Applicable standard
  • Inspection requirements

Example 1 – Weldolet

ASTM A105 Weldolet, 4″ × 2″, Branch SCH 80, MSS SP-97

Example 2 – Threadolet

ASTM A105N Threadolet, 2″ × 1/2″, Class 3000, NPT, MSS SP-97

Example 3 – Socket Weld Olet

ASTM A105 Socket Weld Olet, 3″ × 1″, Class 6000, MSS SP-97

Frequently Asked Questions

What is the difference between a Weldolet and a Threadolet?

A Weldolet has a butt-weld branch connection, while a Threadolet has a threaded female branch outlet.

What is the difference between a Weldolet and a Socket Weld Olet?

A Weldolet connects to the branch pipe by butt welding, while a Socket Weld Olet uses a socket-weld connection.

What standard applies to Weldolets?

MSS SP-97 is the primary standard commonly used for integrally reinforced forged branch outlet fittings.

Is ASME B16.11 the standard for Weldolets?

ASME B16.11 applies to forged socket-welding and threaded fittings.

For integrally reinforced branch outlet fittings such as Weldolets, MSS SP-97 is the more directly applicable product standard.

Is ASTM A105 the same as A105N?

A105 is the material grade.

A105N is commonly used to identify A105 supplied in a normalized condition where required.

Can Weldolets be supplied in stainless steel or alloy steel?

Yes.

Weldolets and other branch outlet fittings can be supplied in carbon steel, Cr-Mo alloy steel, stainless steel, duplex, super duplex and nickel alloys.

ASTM A105 / A105N Branch Outlet Fittings

We manufacture and supply forged branch outlet fittings for oil and gas, petrochemical, power-generation, marine and industrial pressure-piping systems.

Available products include:

  • ASTM A105 Weldolet
  • ASTM A105N Weldolet
  • ASTM A105 Threadolet
  • ASTM A105 Socket Weld Olet
  • ASTM A350 LF2 Weldolet
  • ASTM A182 Alloy Steel Olets
  • Stainless Steel Olets
  • Duplex and Super Duplex Olets
  • Nickel Alloy Olets

For quotation, please provide the run size, branch size, schedule, material, outlet type, quantity and inspection requirements.

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