Ball joints have been around since the beginning of
time. The writer first came across them during World
War II where they were used on steam vessels to accommo-
date pipe expansion and twisting of the hulls. In all probability,
they were used exactly the same way in the First World War, as the
Liberty Ships of World War II were copies of the same vessels.
All in all, that is about a 100 year history with little difference in design except for the
use of better grade materials and improved seals. While thin walled material like Stainless
Steel hoses or the many variations of Stainless Steel expansion joints have very high
safety
factors, there is comfort in knowing you are using a zero thrust product where no
component has a thickness less than the piping itself. One of our overseas reps, in a
country where sabotage was common, commented “They are quite resistant to rifle fire as well.”
We were first exposed to the need for ball joints where thermal expansion design centered
around the use of high pressure steam for heating. There is one huge steam generating station
in lower New York that continues to supply steam for heating in New York City. Any building
owner that purchases this high pressure supply steam must engineer all their high
pressure inlet piping to Con Edison’s (the steam supplier’s) satisfaction. The use of ball
joints to handle thermal movement is a necessity as space is tight and leaves no room for
pipe loops or offsets.
We not only sell our ball joints, but we engineer
the systems as well, should there be no specifica-
tions or if specifications call for design by vendor.
We look forward to working with you.
MASON-MERCER
STOCK
BALL
JOINTS
Bulletin BJ-35
2
TWO BALL JOINTS
When ball joints are installed at each end of a pipe
offset (Fig. 1), the system can accommodate much
larger movements with much lower anchorage
requirements than solid pipe in the same configuration.
COLD SETTING
One way to increase allowable motion is to start out
with the assembly pre-set all the way to the position
when the pipe is cold (Fig. 2). Assuming the total
expansion from Cold (Ambient Temperature) to Hot
is 8 inches, you could set the pipe line 4 inches off
center and design for a 4” rather than an 8” move-
ment leg. The piping is preset 6° off center to 6° past
center. Maximum rated movement is 7.5° off center,
so 6° provides a safety factor.
While the method is perfectly valid, steamfitters are
accustomed to working “Plumb” and the “Cold Set”
instruction can be missed. The method is excellent
but supervision becomes essential and the designer
must decide whether to take the risk.
FOUR BALL JOINTS
In many cases any offset is undesirable, so four ball
joints are used in a loop (Fig. 3A). Using the same
dimension “CC” in both legs, you can accommodate
twice the motion. Reducing the centers 50% would
accommodate the same two joint motion (Fig. 1) with
smaller offset and conserve space as well (Fig. 3B).
DROP IN ELEVATION “Y”
Ball joint movement reduces distance between parallel
piping as shown by “Y” (Figure 1). This dimension
is significant because if the offset is vertical, the
adjacent pipe support could pull out. Therefore a
Mason 30N spring hanger with a minimum deflection
of 4 times “Y” should be installed at the first support
and the second and third locations studied.
STARTING RESISTANCE
Ball joints do not generate any pressure thrust.
However, there is an initial force required to start
motion that controls anchorage.
The force “F” applied to the pipe anchors is directly
related to the distance between Ball Joint Centers
“CC”. (Figure 4). Force “F” diminishes with longer
lever arms needed for larger movements. Four joint
loops have shorter levers for the same movement,
so forces increase (Table 4).
USING SELECTION TABLES
The following tables provide rounded values for easy
selection. For the sake of simplicity, Ball Joint Centers
“CC” are in 6” increments in Table 1 and 3” in Table 2. If
space is tight, interpolate between columns. Calculations
based on Table 5 may save even more space.
The next page provides examples of how to use the
tables with the installations previously discussed.
Figure 1
Figure 3 (A & B)
Hot Cold
Roller
CC
Two
Ball Joint
Installation
Four Ball Joint Installation
Two Ball Joint
Installation
with Cold
Setting
A B
Mason
30N
Spring
Hanger
EE– End to End
CC– Center to
Center of
Rotation
JL– Ball Joint
Length
CR– Ball Joint
Center of
Rotation
L– Intermediate
Pipe Length
X– Pipe
Movement
Y–
Drop in
Elevation
Θ-
Angle of
Rotation
Gray indicates
Starting Position
A– Cold Position
-6° Off Center
B– Hot Position
+6° Off Center
C– Total Movement
12°
EE
CC
L
Y
X
Figure 2
Θ
CR
CC
SP
SP
CC/2
C
Fig 3A
Fig 3B
Mason
BJW250
Ball Joint
4” 4”
8”
JL
SP–
S
preader Pipe
Figure 4
Force “F”
on Anchor
Thermal
Expansion
Force “F”
on Anchor
CC (Lever Arm)
Starting
Resistance
Roller
Roller
Two Ball Joint Installation without Cold Setting
To size an 8” two ball joint offset for 6” movement
at 250 psi, use Table 1. The recommended Center to
Center “CC” is 72”, the Intermediate Pipe Length “L”
is 58” and the Drop in Elevation “Y” is 0.25”. Table 4
shows the Force “F” on Anchor as 1100 lbs. A stain-
less expansion joint thrust is 12,000 lbs., 11 times the
required anchorage for the ball joints.
Two Ball Joint Installation with Cold Setting
To size an 8” two ball joint offset for 6” movement at
250 psi with cold set, use Table 2. The recommended
Center to Center “CC” is 36”, the Intermediate Pipe
Length “L” is 22” and the Drop in Elevation “Y” is 0.13”.
Table 4 shows the Force “F” on Anchor as 2200 lbs.
This force is still much lower than the stainless expan-
sion joint thrust of 12,000 lbs., which is 5.5 times
the required anchorage for the ball joints.
Four Ball Joint Installation without Cold Setting
To size an 8” four ball joint loop for 6” movement,
divide the 6” movement by two, as there are two 3”
movement legs. Using Table 1, 4” column, “CC” is
48”, “L” is 34” and “Y” is 0.17”. To size the spreader
pipe “SP” so the two legs of the loop do not clash, use
Table 3 for a Minimum Spreader Length “SP” of 24”.
“Cold Set” designs are the same as above, using Table 2.
FRICTION FORCES
Pipe Friction is usually taken as 30% of the pipe
weight between anchors. Add this force to Table 4 or
calculated numbers as an additional force on anchors.
CALCULATIONS
For engineers who prefer to do their own calcs.
Refer to Figure 1 for definitions of “CC”, “L”, “CR”,
“EE”, “JL” and “Y”; Table 4 for “F” and “T”; and Table
5for“Θ”.
Two Ball Joint Installation without Cold Setting
Example: 10” steam line, thermal expansion 7”.
CC = X / [Sin (Θ/2)] = 7” / [Sin (12°/2)] = 67”
L = CC - (2 x CR) = 67” - (2 x 7.625”) = 51.75”
EE = L + (2 x JL) = 51.75” + (2 x 16”) = 83.75”
Y
= CC – (CC
2
– X
2
)
1/2
= 67” – (67
2
– 7
2
)
1/2
= 0.37”
For 0.37” movement, we recommend a spring hanger
with a deflection 4 times “Y” or 1.48”, i.e. Mason 1.5”
deflection 30N hanger.
F = 2T / CC = 2 x 6000 ft-lbs / 5.58 ft = 2151 lbs.
Two Ball Joint Installation with Cold Setting
Example: 10” steam line, thermal expansion 9”.
CC=[X/2]/[Sin(Θ/2)]= [9”/2] / [Sin (12°/2)] = 43”
L = CC - (2 x CR) = 43” - (2 x 7.625”) = 27.75”
EE = L + (2 x JL) = 27.75” + (2 x 16”) = 59.75”
Y = CC – (CC
2
– (X/2)
2
)
1/2
= 43” – (43
2
– (9/2)
2
)
1/2
= 0.24”
For 0.24” movement, we recommend a spring hanger
with a deflection 4 times “Y” or 0.96”, i.e. Mason 1”
deflection 30N hanger.
F = 2T / CC = 2 x 6000 ft-lbs/ 3.58 ft = 3352 lbs.
3
TABLE 4
STARTING RESISTANCE AT 250psi See Figure 4
Up to Up to
Pipe Movement “X”
Pipe
Torque
4” 4” 6” 6” 8” 8” 10” 10” 12” 12”
Size “T”
(in) (ft-lbs)
Force “F”* (lbs) on Anchors Without & With Cold Setting
2 200 200 400 133 267 100 200 80 160 67 133
2
1
/2 230 115 230 77 153 58 115 46 92 38 77
3 320 160 320 107 213 80 160 64 128 53 107
4 600 300 600 200 400 150 300 120 240 100 200
5 1000 500 1000 333 667 250 500 200 400 167 333
6 2000 1000 2000 667 1333 500 1000 400 800 333 667
8 3300 1650 3300 1100 2200 825 1650 660 1320 550 1100
10 6000 3000 6000 2000 4000 1500 3000 1200 2400 1000 2000
12 7500 3750 7500 2500 5000 1875 3750 1500 3000 1250 2500
14 11000 5500 11000 3667 7333 2750 5500 2200 4400 1833 3667
Pipe Size Maximum ΘRecommended Angle
(inches) Angle with 20% Safety Factor
2 30° 24°
2
1
/2 - 14 15° 12°
TABLE 5
BALL JOINT ANGULAR MOVEMENT
In all
engineered
systems, a
safety factor
is important.
TABLE 1 “CC”, “L”, and “Y” DIMENSIONS for TWO JOINT
INSTALLATION WITHOUT COLD SETTING See Figure 1
Pipe
Up to
Pipe Movement “X”
Size
4” 5” 6” 7” 8” 9” 10” 11” 12”
(inches) Ball Joint Centers “CC” (inches)
2 24 30 36 42 48 54 60 66 72
2
1
/2-14 48 60 72 84 96 108 120 132 144
Size Intermittent Pipe Length “L” (inches)
2 16 22 28 34 40 46 52 58 64 4 7
2
1
/2 40 52 64 76 88 100 112 124 136 4
1
/8 7
7
/8
3 39 51 63 75 87 99 111 123 135 4
3
/8 8
1
/2
4 38 50 62 74 86 98 110 122 134 5 10
1
/2
5 38 50 62 74 86 98 110 122 134 5
1
/8 10
5
/8
6 37 49 61 73 85 97 109 121 133 5
5
/8 11
7
/8
8 34 46 58 70 82 94 106 118 130 7 14
3
/8
10 33 45 57 69 81 93 105 117 129 7
5
/8 16
12 29 41 53 65 77 89 101 113 125 9
1
/2 18
1
/8
14 27 39 51 63 75 87 99 111 123 10
1
/2 19
1
/4
Size Drop in Elevation “Y” (inches)
2 .34 .42 .50 .59 .67 .76 .84 .92 1.01
2
1
/2-14 .17 .21 .25 .29 .33 .38 .42 .46 .50
CR
Ball Joint
Center of
Rotation
(inches)
JL
Ball
Joint
Length
(inches)
TABLE 2 “CC”, “L”, and “Y” DIMENSIONS for TWO JOINT
INSTALLATION WITH COLD SETTING See Figure 2
Pipe
Up to
Pipe Movement “X”
Size
4” 5” 6” 7” 8” 9” 10” 11” 12”
(inches) Ball Joint Centers “CC” (inches)
2 12 15 18 21 24 27 30 33 36
2
1
/2-14 24 30 36 42 48 54 60 66 72
Size Intermittent Pipe Length “L” (inches)
2 4 7 10 13 16 19 22 25 28 4 7
2
1
/2 16 22 28 34 40 46 52 58 64 4
1
/8 7
7
/8
3 15 21 27 33 39 45 51 57 63 4
3
/8 8
1
/2
4 14 20 26 32 38 44 50 56 62 5 10
1
/2
5 14 20 26 32 38 44 50 56 62 5
1
/8 10
5
/8
6 13 19 25 31 37 43 49 55 61 5
5
/8 11
7
/8
8 10 16 22 28 34 40 46 52 58 7 14
3
/8
10 9 15 21 27 33 39 45 51 57 7
5
/8 16
12 5 11 17 23 29 35 41 47 53 9
1
/2 18
1
/8
14 3 9 15 21 27 33 39 45 51 10
1
/2 19
1
/4
Size Drop in Elevation “Y” (inches)
2 .17 .21 .25 .29 .34 .38 .42 .46 .50
2
1
/2-14 .08 .10 .13 .15 .17 .19 .21 .23 .25
CR
Ball Joint
Center of
Rotation
(inches)
JL
Ball
Joint
Length
(inches)
TABLE 3
MINIMUM SPREADER PIPE “SP”
BETWEEN ELBOWS for FOUR JOINT
INSTALLATION
TO AVOID JOINT CLASHING
See Figure 3
Pipe
Up to
Pipe Movement “X”
Size
4” 5” 6” 7” 8” 9” 10” 11” 12”
(inches) Spreader Pipe “SP” between Elbows (inches)
2 18 21 24 27 30 30 30 33 36
2
1
/2 18 21 24 27 30 30 30 33 36
3 18 21 24 27 30 30 30 33 36
4 24 24 24 27 30 30 30 33 36
5 24 24 24 27 30 30 30 33 36
6 18 21 24 27 30 30 30 33 36
8 18 21 24 27 30 30 30 33 36
10 18 21 24 27 24 27 30 33 36
12 18 21 24 27 24 27 30 33 36
14 12 15 18 21 24 24 24 27 30
SP
Wu1301
01/13
BJW250
BALL JOINT with
WELD ENDS
SEAL AND PACKING DETAIL
PACKING INLET
AND SEAL VALVE IN
CLOSED POSITION–
ROTATE 90° TO OPEN
INJECTED FLAKE GRAFOIL
PACKING (Filled at factory,
may be repacked in field
using hand pump)
SOCKET
ASSEMBLY
JL
STEEL BALL 1 MIL
HARD CHROME
PLATING
PACKING
INJECTION
PORT
(See Detail)
STEEL BALL
WELD END–
WELD INTERMEDIATE
PIPE TO THIS END
HD
FD
MAM
REMOVE
PLUG TO
INJECT
PACKING
FINISH:
Blue Enamel Paint
JL CR FD HD MD MAM Maximum Starting
Type Pipe Joint Center of Flange Hub Max. Max. Angular
Pressure Resistance Number Ship
& Size Length Rotation Diameter Diameter Diameter
Movement @480°F Torque of Weight
Size (inches) (inches) (inches) (inches) (inches) (inches) (degrees)
(psi) (ft-lbs) Ports (lbs)
BJW250
-2 2 7 4 – 5
1
/4 9
1
/2 30 250 200 2 16
BJW250
-2
1
/2 2
1
/2 7
7
/8 4
1
/8 – 6 10
1
/4 15 250 230 2 23
BJW250
-3 3 8
1
/2 4
3
/8 – 6
1
/2 10
3
/4 15 250 320 2 26
BJW250
-4 4 10
1
/2 5 10
7
/8 7
7
/8 12
1
/8 15 250 600 4 72
BJW250
-5 5 10
5
/8 5
1
/8 12 9 13
1
/4 15 250 1000 4 80
BJW250
-6 6 11
7
/8 5
5
/8 13
1
/4 10
1
/2 14
3
/4 15 250 2000 5 113
BJW250
-8 8 14
3
/8 7 16 13 17
1
/4 15 250 3300 6 189
BJW250
-10 10 16 7
5
/8 19
3
/8 16 20
1
/4 15 250 6000 7 280
BJW250
-12 12 18
1
/8 9
1
/2 22 18
1
/2 22
3
/4 15 250 7500 8 361
BJW250
-14 14 19
1
/4 10
1
/2 23
5
/8 20 24
1
/4 15 250 11000 9 443
BJW250 DIMENSIONS AND PRESSURE RATINGS
STEEL
BALL
RETAINER
1 MIL
CHROMED
STEEL SEAL
RETENTION
RINGS
HARD
GRAPHITE
CONTAINMENT
SEAL
4
MASON – MERCER
350 Rabro Drive, Hauppauge, NY 11788 • FAX 631/348-0279
MASON– 631/348-0282 • Email [email protected] • Website www.Mason-Ind.com
MERCER– 631/582-1524 • Email [email protected] • Website www.Mercer-Rubber.com
BALL JOINT SPECIFICATION:
Steel Ball Joints shall have weld ends or fixed and float-
ing flanges. The thrust free, ball and socket arrange-
ment shall allow 360° of intermittent rotation and a
minimum rocking motion of ± 7.5 degrees. Seals are
guaranteed by the high pressure injection of graphite
packing in a cavity between reinforced hard graphite
and steel rings.
The ball and steel seal retention rings shall be plated with
a minimum 1 mil thickness of crack free hard chrome.
The socket must incorporate an adequate number of
packing cylinders for uniform distribution of the graphite
seal. All cylinders must incorporate a valve to prevent
blowback should pumping additional sealing material
become necessary while under full line pressure.
Minimum ratings are 250 psi (17 Bar) @ 480°F (250°C).
Certifications must include:
1. Either manufacturer’s published information or calcu-
lations by a P.E. to verify length of spool pieces and the
distance between centers of ball joints for the motion
with a reasonable safety factor.
2. The friction force at the start of motion to be resisted
by the anchors.
Should the consulting firm prefer to indicate location
of anchors and ball joints as preliminary and leave final
selections to job site conditions, the manufacturer must
have a P.E. on staff with a minimum of 5 years pip-
ing design experience to submit final details to allow
motion as well as the force on the anchors to overcome
starting friction.
Ball Joints shall be weld end BJW or Flanged BJF as
manufactured by Mason Industries, Inc.
MD
Maintain 4” minimum clearance
around MD to allow for repack-
ing. Packing can be injected under
full line pressure when required.
Packing to be Flake Grafoil.
CR