Threads and Sealing Methods

Identifying Threads, Threads, Sealing Methods and Industrial Fittings

Module Objectives 

Explain the basic thread characteristics necessary to identify threads

Module Objectives  

Explain the basic thread characteristics necessary to identify threads Differentiate between and identify various types of threads used on industrial fittings

Module Objectives   

Explain the basic thread characteristics necessary to identify threads Differentiate between and identify various types of threads used on industrial fittings Explain the various sealing methods used for the different fittings

Module Objectives    

Explain the basic thread characteristics necessary to identify threads Differentiate between and identify various types of threads used on industrial fittings Explain the various sealing methods used for the different fittings Identify different types of fittings being used in the industrial market place

ead Thr ead Char acte acter istics istics

Thr ead ead

Char acte acter istics istics

Pitch  Thread

thread

pitch is the distance between a single

Thr ead ead

Char acte acter istics istics

Pitch:  Pitch

is sometimes written as the number of  threads within one inch distance 

e.g. 8 threads per inch

Thr ead ead

Char acte acter istics istics

Flank Angle and Taper Angle :

Thr ead ead Crest

Char acte acter istics istics

and Root:

Root Crest

Thr ead ead Major

Char acte acter istics istics

Diameter or OD:

ead Thr ead

Style and Function

Thr ead ead Port

Styles

End Threads:

 Parallel

Par all allel

Thr ead ead

Functions

Par all allel Threads:  Parallel



threads only serve the function of  holding in the fitting Sealing is achieved by some other means, such as with an O-ring

Thr ead ead Port

Styles

End Threads:

 Tapered

Tapered

Thr ead ead

Function

Tapered Threads:  Tapered

threads serve two functions: 

For For hol holdi ding ng in the the fitting



Sealin Sealing g (even (even though though sealing is usually assisted with additional sealant)

ead Thr ead

ID

Tools

Thr ead ead  MIK-1   

ID

Tools

kit  Port Boards Known Threads Markings and Tables

Thr ead ead MIK-1

ID

Tools

kit 

 Caliper  Thread   

gages Thread profiles Instruction booklet  Nose angle indicator

Thr ead ead MIK-1

ID

Tools

kit 

 Caliper 

Used to measure outside and inside diameter in either inch or metric units

Thr ead ead MIK-1

Tools

kit 

 Thread 

ID

gages

Used to compare thread form to determine pitch

Thr ead ead MIK-1

Tools

kit 

 Thread 

ID

profiles

Used to shadow pipe threads for determining nominal size

Thr ead ead MIK-1 

ID

Tools

kit 

Nose angle indicator 

Used to determine whether nose angle or seat se at is 37° 37° or 45° 45°

Thr ead ead MIK-1 

ID

Tools

kit 

Instruction booklet  (4303-B1)  Contains

specifications for various thread forms

Thr ead ead Port 

ID

Tools

Board Used to determine male thread size based on comparison with known threads

Thr ead ead

ID

Tools

Other Known Threads  Tube

nuts or other components where threads can be used for comparison

Thr ead ead Markings  

ID

Tools

and Tables

In some cases, fittings are marked with a cross reference for threads Tables can be used to identify threads based on given characteristics

Identifying

eads Thr eads

Identifying Steps

eads Thr eads

for Identifying Thread Forms:

1a. Verify if parallel or tapered   Visual inspection

Identifying Steps

eads Thr eads

for Identifying Thread Forms:

1b. Verify if parallel or tapered  Compare with a known parallel

Identifying Steps

eads Thr eads

for Identifying Thread Forms: Forms:

2. Determine thread pitch  Use thread gages

Bad Fit

Good

Fit

Identifying Steps

eads Thr eads

for Identifying Thread Forms:

3a. Determine size  Measure

profile

with caliper or compare with thread

Identifying

Thr eads eads

Steps

for Identifying Thread Forms 3b. Determine Size  Compare

with Profile

Identifying Steps

Thr eads eads

for Identifying Thread Forms:

4. Define thread  Threads 

are called out according to the type of 

thread They usually follow a standard pattern and this is how they may appear on a print 

Identifying Steps

Thr eads eads

for Identifying Thread Forms:

4. Define thread  NPT/NPTF 

Example:

- Ame merrican Pipe Thread 1/4-18 NPT

1/4 = nominal size  18 = pitch (threads per inch)  NPT or NPTF usually specified or NPT /NPTF where it does not matter if it is either one 

Identifying Steps

Thr eads eads

for Identifying Thread Forms:

4. Define thread  UN /UNF 

- Unifie Unified d (SAE (SAE Straig Straight  ht Thread) Example: 9/16-18 UN UNF 9/16 = actual size  18 = pitch (threads per inch)  UN or UNF usually specified or UN/UNF where it  does not matter  UNF is usually used for thread pitch above 1 2 TPI 

Identifying Steps

Thr eads eads

for Identifying Thread Forms:

4. Define thread  BSPT 

- Brit Britis ish h Stan Standa dard rd Pipe, Tapered Example: R3/8 R signifies tapered  3/8 = nominal size  The pitch is usually assumed based on known standard  Japanese taper thread would be written as PT 3/8 

Identifying Steps

Thr eads eads

for Identifying Thread Forms:

4. Define thread - Brit Britis ish h Stan Standa dard rd Pipe, Parallel Example: G3/4

 BSPP 

G signifies parallel  3/4 = nominal size  The pitch is usually assumed based on known standard  Japanese parallel thread would be written as PF 3/8 

Identifying Steps

Thr eads eads

for Identifying Thread Forms:

4. Define thread  Metric Parallel 

Example:

1.5 M22X 1.5

signifies metric  22 = actual size in mm  1.5 = pitch (distance between threads in mm) M

Identifying Steps

Thr eads eads

for Identifying Thread Forms:

4. Define thread  Metric 

Tapered Example: M10X 1 keg (or tapered) signifies metric  10 = actual size in mm  1 = pitch (distance between threads in mm)  keg is the abbreviation for the German word meaning tapered and if the thread is tapered, it will be specified M

Por t

End Sealing Methods

Por t 

End Sealing Methods

Female Port   O-ring in chamfer  Available

with

 UN/UNF (SAE J1926)  Metric (ISO 6149)  BSPP (JIS B2351)

Por t 

End Sealing Methods

O-ring in chamfer (Male end)  Most

reliable form of  sealing   Available in adjustable fittings 

ISO 6149 has special identification

Por t 

End Sealing Methods

Female Port   Spot face sealing  Available

with

 Metric (DIN 385 2-1)  BSPP (DIN 3852-2)  Wide

variety of  interchangeable interchangeable male m ale ends

Por t 

End Sealing Methods

O-ring in groove  DIN

3852 Type E

 O-ring

not round in cross section  Adjustable not possible  Second in pressure holding capacity

Por t 

End Sealing Methods

O-ring w/ retaining ring  DIN

3852 Type G & H

 Separate

metal ring surrounding o-ring  Adjustable fittings are type H

Por t 

End Sealing Methods

Bonded Seal  DIN

3852 Type D

 Elastomer

bonded to metal ring  Undercut on fitting has taper angle  Adjustable not possible

Por t 

End Sealing Methods

Hard metal seal  DIN

3852

 Typically

used on Banjo fittings  Seals by coining surface of port   Limited reusability  Useful for extreme temperatures  Adjustable not possible

Por t 

End Sealing Methods

Soft Metal Seal  DIN

3852 Type A

 Seal

material usually copper  Adjustable not possible  Undercut area has taper angle

Por t

End Sealing Methods

 Cutting  DIN

Face Seal

3852 Type B

 Sharp

edge on fitting coins spotface for sealing  Limited reusability  Adjustable not possible  Useful for extreme temperatures

Por t 

End Sealing Methods

Female Port   Taper

threads

 Available

with

 NPT /NPTF (SAE 476)  BSPT (DIN 3852-2)  Metric taper (DIN 3852-1)  Sometimes

female port has parallel threads

 Tapered male into female parallel allowed

Por t

End Sealing Methods

 Taper

threads

 Sealing

initiated by thread interference  Additional sealant usually required  Prone to fatigue failure  Prone to galling

Tube/Hose

End Sealing Methods

Tube

End Identification

Tube/Hose       

Ends

O-ring face seal (flat face seal) 37° flare 45° flare flarel eles esss 24° flar JIS JIS 30° 30° flar flare e and and 60° 60° cone cone BSI (BSPP) 60 60° cone NPSM /NPT

Tube

End Identification

Tube/Hose 

End

O-ring face seal SAE J1453  ISO 8434-3  UN/UNF Thread  Hose,Inch or metric tube 

Tube

End Identification

Tube/Hose 

End

37° flare SAE J514  ISO 8434-2  UN/UNF Thread  Hose, Inch or metric tube 

Tube

End Identification

Tube/Hose 

End

45° flare SAE J512  UN/UNF Thread  Hose, Inch tube 

Tube

End Identification

Tube/Hose  24°

End

flar flarel eles esss

SAE J514  UN/UNF Thread  Hose, Inch Tube 

Tube

End Identification

Tube/Hose  24°

End

flar flarel eles esss

DIN 2353  ISO 8434-1  Metric Thread  Hose, Metric Tube  3 pressure series 

Tube

End Identification

Hose End 

JIS Cone B8363  BSPP Thread  60° cone  Hose connection 

Tube

End Identification

Hose End 

JIS Flare B8363  BSPP Thread  30° 30° flar flare e  Hose connection 

Tube

End Identification

Hose End 

Komatsu Flare  Metric Thread

1.5 mm pitch (all sizes)  30° 30° flar flare e  Hose connection 

Tube

End Identification

Hose/Port End 

BSPP cone BS B5200  BSPP thread  60° cone  Hose connection 

Tube

End Identification

Hose/Port End 

NPTF/NPSM SAE J516  NPT /NPTF male thread  NPSM female thread 30° cham chamfe ferr or 60° 60° cone cone  30°  Hose connection 

Identifying Met r ic ic 24° Flar eless eless Fittings

Identifying Metr ic ic 24° Flar eless eless Fittings 

Identify markings  Manufacturers  Material  

code Tube size Pressure series

logo

Identifying Metr ic ic 24° Flar eless eless Fittings 

Determine Tube Size  Measure

sleeve ID

Identifying Metr ic ic 24° Flar eless eless Fittings 

Determine Tube Size  Measure

tube OD

Identifying Metr ic ic 24° Flar eless eless Fittings 

Determine Tube Size  Measure

fitting throat 

Identifying Metr ic ic 24° Flar eless eless Fittings 

Determine Tube Size  Measure

opening in back of nut 

Identifying Metr ic ic 24° Flar eless eless Fittings 

Determine thread pitch and size

Identifying Metr ic 24° Flar eless eless Fittings   Verify

with specification table

Tube Tube OD (mm) (mm) Press Pressure Series 4 LL 6 LL 8 LL 10 LL 12 LL

Thread Thread size M8X1 M10X1 M12X1 M14X1 M16X1

6

L

M 12X1. 5

8

L

M 14X1. 5

10

L

M 16X1. 5

12

L

M 18X1. 5

15

L

M 22X1. 5

18

L

M 26X1. 5

22

L

M30X2

28

L

M36X2

35

L

M45X2

42

L

M52X2

6 8 10 12 14 16 20 25 30 38

S S S S S S S S S S

M14X1.5 M16X1.5 M18X1.5 M20X1.5 M22X1.5 M24X1.5 M30X2 M36X2 M42X2 M52X2

JIS

and BSPP 60° Cone Fittings

JIS 

and BSPP 60° 60° Cone Cone Fitt Fittin ings gs

Differences  Thread    

length Chamfer diameter Undercut area Function (dual vs single) Interchangeability?

Hands on Exer cise cise

Standar ds ds Activity and Industr y

ends Tr ends

Standar ds ds Activity  Merging

of BSI and JIS 60° Cone Adapters



ISO 16030 Pneumatic BSPP Port 



High Pressure

Multi-Bolt

Round Flanges

Industr y

Tr ends ends

 Metric Tube  

(plated) Elastomeric Seal EO-2  Machine Tool



Builders

ISO 6149  Ag 

Equipment  Manufacturers Engine Manufacturers

What·s

available Fr om om TFD

What·s K4

Available f r  o rom   m

TFD

Adapter s

Tube

Fabr icating icating Equipment

Metr ic ic Tube EO

and EO-2 Fittings & Accessor ies ies

JIS

Fittings

sion Conver sion

Adapter s and

Metr ic ic Tr iple-lok iple-lok

ic Metr ic

Seal-lok

ic Tube Metr ic

Clamps

Plugs