Definition and Details of Threaded Flange:

Threaded Flanges are used for special circumstances with their main advantage being that they can be attached to the pipe without welding. Sometimes a seal weld is also used in conjunction with the threaded connection.

Although still available in most sizes and pressure ratings, screwed fittings today are used almost exclusively in smaller pipe sizes.

A threaded flange or fitting is not suitable for a pipe system with thin wall thickness, because cutting thread on a pipe is not possible. Thus, thicker wall thickness must be chosen.

ASME B31.3 Piping Guide says:
Where steel pipe is threaded and used for steam service above 250 psi or for water service above 100 psi with water temperatures above 220° F, the pipe shall be seamless and have a thickness at least equal to schedule 80 of ASME B36.10.

Threaded Flange Vs Slip On Flange

 

Threaded Flanges (Screwed flanges)are similar to slip-on flanges in outline, but the bore is threaded, thus enabling assembly without welding. This obviously limits its application to relatively low pressure piping systems. Threaded Flanges may be welded around the joint after assembly, but this is not considered a satisfactory method of increasing the flanges’ pressure applications. Threaded flange use in low press condition usually.

Threaded Flanges Size and Pressure :

Size: 1/2-78 inch (DN15-DN2000)
Pressure: ANSI class 150,300,600,1500,2500, DIN PN6,PN10,PN16,PN25,PN40,PN64,PN100,PN160
Surface Treatment: Anti-rust Oil, Transparent/Yellow/Black Anti-rust Paint,Zinc,Hot dipped Galvanized. 

Threaded Flanges Standard 

ASME B16.5 Pipe Flanges and Flanged Fittings
ASME B16.47 Series A Steel Flanges NPS 26 Through NPS 60
API 605/ASME B16.47 Series B Steel Flanges NPS 26 Through NPS 60
BS EN 1759 Flanges and their joints. Circular flanges for pipes, valves, fittings and accessories, class-designated. Steel flanges
EN 1092 Circular flanges for pipes, valves, fittings

BS 3293 Carbon steel pipe flanges For the petroleum industry

BS 4504 Circular flanges for pipes,valves and fittings
JIS B2220 Steel pipe flanges

Threaded Flange Materials:

Carbon Steel Blind Flange:
A105 GradeⅠ Carbon Steel Blind Flange
A105 GradeⅡ Carbon Steel Blind Flange
Alloy Steels Blind Flange:
A182 Grade F1 Alloy Steel Blind Flange
A182 Grade F5 Alloy Steel Blind Flange
A182 Grade F7 Alloy Steel Blind Flange
A182 Grade F9 Alloy Steel Blind Flange
A182 Grade F11 Alloy Steel Blind Flange
A182 Grade F12 Alloy Steel Blind Flange
A182 Grade F22 Alloy Steels Blind Flange
Low-Temperat Steel Blind Flange:
A350 Grade LF1 Low-Temperat Steel Blind Flange
A350 Grade LF3 Low-Temperat Steel Blind Flange
A350 Grade LF4 Low-Temperat Steel Blind Flange
A350 Grade LF6 Low-Temperat Steel Blind Flange
A350 Grade LF8 Low-Temperat Steel Blind Flange
Stainless Steel Blind Flange:
A182 Grade F304 Stainless Steel Blind Flange
A182 Grade F304H Stainless Steel Blind Flange
A182 Grade F304L Stainless Steel Blind Flange
A182 Grade F316 Stainless Steel Blind Flange
A182 Grade F316H Stainless Steel Blind Flange
A182 Grade F316L Stainless Steel Blind Flange
A182 Grade F321 Stainless Steel Blind Flange
A182 Grade F321H Stainless Steel Blind Flange
A182 Grade F347 Stainless Steel Blind Flange
A182 Grade F347H Stainless Steel Blind Flange