Uniform Mechanical Code- 2009 Appendix a 6-2

8/14/2019 Uniform Mechanical Code- 2009 Appendix a 6-2

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A.6.201 Scope.

The performance criteria and requirements hereincontemplate a duct that is a structural assemblyhaving the capacity to support occupant healthand safety while minimizing its own contributionto property damage under emergency conditions.Ducts can supply fresh or treated air in support oflife and health, can convey products of combustionaway from a fire zone, can maintain a pressuredifferential that facilitates evacuation and reducesthe spread of fire and smoke, and can facilitate

firefighter access to a fire source.

A.6.202 Definitions.

Closure The joining components on duct surfacesthat are subjected to a pressure differential acrossthe duct wall, including mechanical locks andmetallic and nonmetallic materials used as fillers orsealers whether on straight sections of ducts orfittings or used in connection of ducts or fittings toother apparatus. Closure shall also pertain topenetrations of duct walls (such as by screws, rivets,pipes, electrical conduits, etc.).

Closure Failure Any structural failure at a closure

and also any loss of adhesive bond, creep,displacement, or other deterioration of closurematerials and methods that results in an increase inair leakage above an allowable level and any

behavior contributing to accelerated aging of theclosure systems.

D uct A ssembl y The completed compositeconnected assembly of straight sections, fittings, andaccessories attached to or occurring in the perimeterof an air passageway that is used for supply air,exhaust air, or recirculated air mode. Thepassageway need not be continuous.

Note: Where apparatus, ceiling plenums, room

boundaries, shafts, air terminals, etc., form a part ofthe passageways, such are not subject to theperformance requirements in this standard, but arenot prohibited from being made subject to similarrequirements.

Metal Duct A duct constructed of galvanizedsteel, uncoated steel, stainless steel, or aluminummaterial of commercial grade. Accessories andreinforcements are not required by this standard to

be of the same material as the duct wall, but they

must be electrolytically compatible and shall notreduce the performance levels for strength and tightclosure of ducts.

Structural Failure Any visible and measurablerupture, collapse, buckling, or other permanentdeformation or separation of the elements in the ductassembly.

A.6.203 Performance Requirements for Ducts.

(A) Pressure. Structural failure or closure failure of

a duct assembly shall not occur at 150 percent of thedesigned operating pressure classification whensupported at the maximum recommendedsupport spacing.

(B) Support Spacing. Structural failure or closurefailure of duct assembly shall not occur whensupported at twice the maximum recommendedsupport spacing and atmospheric pressure ismaintained inside the ducts.

(C) Deflection, Longitudinal. The maximumallowable deflection of rectangular duct walls atdesign pressure classification shall not exceedthe following:

Duct Dimension Deflection

12" down (305 mm) 1/2" (12.7 mm)

13" to 18" (330 to 457 mm) 5/8" (15.9 mm)

19" to 24" (483 to 610 mm) 3/4" (19.1 mm)

over 24" (over 610 mm) 1" (25.4 mm)

The deflection reference plane is thatpassing through two adjacent corners of theduct. For cross-broken ducts, the measurementpoint shall be on the centerline of the duct at apoint 1/8 of the duct width or reinforcementinterval or joint spacing if unreinforced,

whichever is greater, from the intersection of thecross-breaks. For cross-broken ducts, theallowable wall deflection shall be increased by50 percent of the deflection set measured atatmospheric pressure level in the duct.

(D) Deflection, Transverse. The maximumallowable deflection for rectangular duct transverse

joint systems and intermediate reinforcements shallbe 1/4 inch (6.4 mm) for duct widths of 100 inches

283

APPENDIX A

UNIFORM MECHANICAL CODE STANDARD NO. 6-2STANDARD FOR METAL DUCTS

Based on the first edition, 1995 HVAC Duct Construction Standards, Metal and Flexible, published by theSheet Metal and Air Conditioning Contractors National Association.

See Sections 506.2, 602.1, and 602.5 of the Uniform Mechanical Code.


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(2,540 mm) or less and shall be 0.3 percent of the spanfor greater widths. In any case, the allowabledeflection shall not be construed as permitting suchmembers to exceed 60 percent of their yield stress.

(E) Allowable Stress. Loads imposed by fabricatedductweight designedpressure differential across the

duct wall, bending moment created by supports,and 1/2 pound per square foot (2.4 kg/m2) ofinsulation weight shall not exceed 60 percent of theyield stress of the metals in the duct and itsconnections. Other internal and external loads arenot accounted for by this standard.

(F) Cyclical Loading Resistance. Duct assembliesshall be capable of withstanding a daily on-offcycle of operation without structural failure.

(G) Air-Tightness. Closures for ducts shall besubstantially air-tight.

A.6.204 Support Requirements for Ducts.

(A) Method and Interval.The support spacinginterval and method of contact with the duct

assembly shall be selected to avoid structuralfailure or closure failure in the duct.

(B) Allowable Stress in Supports. Supports shallnot be subjected to more than 60 percent of theiryield stress.

(C) Safety Factor. The upper attachment of a ductsuspension (hanging) system to a buildingstructure shall have a safety factor of at leastfour (4) based on ultimate failure (pullout) load.

(D) Loading. Supports shall account for loadsidentified in Section A. 6.203(A).

(E) Fasteni ng Loads. T he l oc at io n a ndarrangement of all fastenings in the supportsystem shall be selected to avoid failure intensile, compressive, shear, and flexure modes.

(F) Corrosion Control. The support system shallnot cause corrosion by galvanic (electrolytic)action at points of contact with the duct.

(G) Character of Support System. The supportsystem shall not penetrate enclosures containingfluids or electrical wiring in such a manner as tocreate a hazard, nor shall they penetrate a load-

bearing member in such a manner as to causeexcessive loading on the member.

A.6.205 Complying Systems.Tables 6-2-A through 6-2-Q typify duct constructionconforming with this standard. Throughout thetables in this standard, the minimum thickness ininches for galvanized sheet gauge numbers is used.

UNIFORM MECHANICAL CODE

284

APPENDIX A, UMC STANDARD 6-2


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STANDARD FOR METAL DUCTS APPENDIX A, UMC STANDARD 6-2

285

TABLE 6-2-ARectangular Duct Hangers, Minimum Size

Maximum Pair at 10 ft. Spacing Pair at 8 ft. Spacing Pair at 5 ft. Spacing Pair at 4 ft. Spacing

Half of

Duct Perimeter Strap Wire/Rod Strap Wire/Rod Strap Wire/Rod Strap Wire/Rod

P=30" 1" x 0.030 10 ga. 1" x 0.030 10 ga. 1" x 0.030 12 ga. 1" x 0.030 12 ga.2 (1" x 22 ga.) (0.135") (1" x 22 ga.) (0.135") (1" x 22 ga.) (0.106") (1" x 22 ga.) (0.106")

P=72" 1" x 0.047 3/8" 1" x 0.036 1/4" 1" x 0.030 1/4" 1" x 0.030 1/4"2 (1" x 18 ga.) (1" x 20 ga.) (1" x 22 ga.) (1" x 22 ga.)

P=96" 1" x 0.058 3/8" 1" x 0.047 3/8" 1" x 0.036 3/8" 1" x 0.030 1/4"2 (1" x 16 ga.) (1" x 18 ga.) (1" x 20 ga.) (1" x 22 ga.)

P=120" 1-1/2" x 0.058 1/2" 1" x 0.058 3/8" 1" x 0.047 3/8" 1" x 0.036 1/4"2 (1-1/2" x 16 ga.) (1" x 16 ga.) (1" x 18 ga.) (1" x 20 ga.)

P=168" 1-1/2" x 0.058 1/2" 1" x 0.058 1/2" 1" x 0.058 3/8" 1" x 0.047 3/8"2 (1-1/2" x 16 ga.) (1-1/2" x 16 ga.) (1" x 16 ga.) (1" x 18 ga.)

P=192" 1/2" 1-1/2" x 0.058 1/2" 1" x 0.058 3/8" 1" x 0.058 3/8"2 (1-1/2" x 16 ga.) (1" x 16 ga.) (1" x 16 ga.)

P=193" up Special analysis required2

Single Hanger Maximum Allowable Load

When straps are lap-joined, use these minimum fasteners: Strap Wire or Rod (Dia.)

1 x 0.047", 0.036", 0.030 - two No. 10 or one 1/4 bolt 1" x 0.030"260 lbs. 0.106"80 lbs.1" x 0.058" two 1/4" dia. 1" x 0.036"320 lbs. 0.135"120 lbs.1-1/2" x 0.058" - two 3/8" dia. 1" x 0.047"420 lbs. 0.162"160 lbs.Place fasteners in series, not side by side. 1" x 0.058"700 lbs. 1/4''270 lbs.

1-1/2" x 0.058"1,100 lbs. 3/8"680 lbs.1/2''1,250 lbs.5/8"2,000 lbs.3/4"3,000 lbs.

Notes:

1. Dimensions other than gauge are in inches.2. Tables allow for duct weight 1 lb./sf (4.8 kg/m2), insulation weight normal reinforcement, and trapeze weight, but no external

loads.3. Straps are galvanized steel; other materials are uncoated steel.4. Allowable loads for P/2 assume that ducts are 0.058 (16 ga.) (1.47 mm) maximum, except that when maximum duct dimension

(w) is over 60" (1,524 mm), then P/2 maximum is 1.25 w.5. For trapeze sizes see Table 6-2-B.6. Twelve [0.081 in. (2.05 mm)], 10 [0.102 in. (2.59 mm)], or 8 [0.128 in. (3.25 mm)] ga. wire is steel of black-annealed, bright basic,

or galvanized type.


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286


TABLE 6-2-B

Allowable Loads for Trapeze Angles (for Rectangular Ducts)

18" 80 150 180 350 510 650 940 1,230 1,500 1,96024" 75 150 180 350 510 650 940 1,230 1,500 1,96030" 70 150 180 350 510 650 940 1,230 1,500 1,96036" 60 130 160 340 500 620 920 1,200 1,480 1,94042" 40 110 140 320 480 610 900 1,190 1,470 1,93048" 80 110 290 450 580 870 1,160 1,440 1,900

54" 40 70 250 400 540 840 1,120 1,400 1,86060" 190 350 490 780 1,060 1,340 1,80066" 100 270 400 700 980 1,260 1,72072" 190 320 620 900 1,180 1,64078" 80 210 500 790 1,070 1,53084" 80 380 660 940 1,40096" 320 600 1,060

108" 150 610

Note: Loads above assume that a hanger rod is 6" max. distance from duct side.

1

x

1

x

0.0

58"(16

ga.)

1

x

1

x

1/8"

1-1/2x1-1/2x0.0

58"(16ga.)

1-1/2

x

1-1/2

x

1/8

"

1-1/2

x

1-1/2

x

3/1

6"

1-1/2x1-1/2x1/4"or2x2x1/8"

2

x

2

x

3/16"

2

x

2

x

1/4"

2-1/2

x

2-1/2

x

3/1

6"

2-1/2

x

2-1/2

x

1/4

"

Length

inches x 25.4 = mmpounds x 0.454 = kg

feet x 304.8 = mm

TABLE 6-2-C

Round Duct Hangers

Duct Maximum WireDiameter Spacing Diameter Rod Strap

10" down 12' One 12 ga. 1/4" 1" x 0.030 (22 ga.)11 to 18" 12' Two 12 ga. 1/4" 1" x 0.030 (22 ga.)

or one 8 ga.19 to 24" 12' Two 10 ga. 1/4" 1" x 0.030 (22 ga.)25 to 36" 12' Two 8 ga. 3/8" 1" x 0.036 (20 ga.)37 to 50" 12' fi Two 3/8" Two 1" x 0.036 (20 ga.)51 to 80" 12' fi Two 3/8" Two 1" x 0.047 (18 ga.)

81 to 94" 12' fi Two 3/8" Two 1" x 0.058 (16 ga.)

Table 6-2-D

Flat Oval Duct Construction

Inches (Gauge)

Duct Width Spiral Lock Seam Duct Longitudinal Seam Duct Fittings

To 24" 0.024 (24) 0.036 (20) 0.036 (20)25" to 36" 0.030 (22) 0.036 (20) 0.036 (20)37" to 48" 0.030 (22) 0.047 (18) 0.047 (18)49" to 60" 0.036 (20) 0.047 (18) 0.047 (18)61" to 70" 0.036 (20) 0.058 (16) 0.058 (16)

71" and up 0.047 (18) 0.058 (16) 0.058 (16)


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287

TABLE 6-2-E

Round Duct Gauge Selection for Galvanized Steel

Maximum 2" W.G. (498 Pa) Maximum 10" W.G. (2.5 kPa) Maximum 2" W.G. (498 Pa)

Static Positive Static Positive Static Negative

Duct Diameter, Spiral Seam, Longitudinal Seam, Spiral Seam, Longitudinal Seam, Spiral Seam, Longitudinal Seam,Inch es Inc he s (Ga ug e) Inc hes (Gau ge ) Inc he s (Ga ug e) Inc he s (Ga ug e) Inc hes (Gau ge ) Inch es (Gau ge )

3 thru 8 0.016 (28) 0.016 (28) 0.019 (26) 0.024 (24) 0.016 (28) 0.024 (24)9 thru 14 0.016 (28) 0.019 (26) 0.019 (26) 0.024 (24) 0.019 (26) 0.024 (24)

15 thru 26 0.019 (26) 0.024 (24) 0.024 (24) 0.030 (22) 0.024 (24) 0.030 (22)27 thru 36 0.024 (24) 0.030 (22) 0.030 (22) 0.036 (20) 0.030 (22) 0.036 (20)37 thru 50 0.030 (22) 0.036 (20) 0.036 (20) 0.036 (20) 0.036 (20) 0.047 (18)

51 thru 60 0.036 (20) 0.047 (18) 0.047 (18) 0.047 (18) 0.047 (18) 0.058 (16)61 thru 84 0.047 (18) 0.058 (16) 0.047 (18) 0.058 (16) 0.058 (16) 0.070 (14)


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288


TABLE6-2-G

RectangularDuctTransverseReinforcementfor

DuctMaterialThicknesse

sfrom

0.0

30"(22ga.)

(0.7

6mm)to

0.0

19"(26ga.)

(0.4

8mm)

PressureClass

1/2"

1/

2"

1"

1"

2"

2"

1/2"

1/2"

1"

1"

2"

2"

1/2"

1/2"

1"

1"

2"

2"

(WaterGauge)

DuctThickness

0.0

30"0.0

30"

0.030"0.030"

0.0

30"

0.0

30"

0.024"

0.024"0.024"

0.024"

0.02

4"

0.0

24"0.019"0.019"0.019"0.0

19"0.019"0.0

19"

Inches(Gauge)

(22)

(2

2)

(22)

(22)

(22)

(22)

(24)

(24)

(24)

(24)

(24

)

(24)

(26)

(26)

(26)

(2

6)

(26)

(26)

DuctDimensions

7"dn.

8-10"

11,1

2"

A/5D

A/8D

13,1

4"

A/5

D

A/8D

A/10DA/

8D

A/5D

A/4D

15,1

6"

A/10D

A/8D

A/10D

A/8D

A/5

D

A/8D

A/5D

A/

8D

A/5D

A/4D

17,1

8"

A/10D

A/8D

A/10D

A/8D

A/5

D

A/8D

A/5D

A/

8D

A/5D

A/4D

19,2

0"

A/10D

A/8D

A/5D

B/8

A/10D

A/8D

A/5

D

A/4DA/10DA/8D

A/5D

A/

8D

A/5D

A/4D

21,2

2"

A/10

A/8

A/5

B/8

A/10

A/8

A/10

A/8

A/

5

A/4

A/10

A/8

A/5

A

/4

A/5

A/4

23,2

4"

B/10

B/8

B/5

C/8

A/10

A/8

B/10

B/8

B/5

B/4

A/10

A/8

A/5

A

/4

B/5

B/4

25,2

6"

A/10

A

/8

B/10

B/8

B/5

C/8

A/10

A/8

A/5

B/8

B/5

B/4

A/10

A/8

A/5

A

/4

B/5

B/4

27,2

8"

B/10

B/8

C/10

C/8

C/5

B/4

B/10

B/8

B/5

C/8

C/

5

B/4

B/5

B/8

B/5

B/4

B/2-1/2

B/4

29,3

0"

B/10

B/8

C/10

C/8

C/5

C/4

B/10

B/8

B/5

C/8

C/

5

C/4

B/5

B/8

B/5

B/4

C/2-1/2

C/4

31-36"

C/10

C/8

C/5

D/8

D/5

D/4

C/5

C/8

C/5

C/4

D/2-1/2

D/4

C/5

C/4

C/5

C

/4

37-42"

D/5

D/8

D/5

D/4

E/5

E/4

D/5

D/8

D/5

D/4

E/2-1/2

E/4

D/5

C/4

D/2-1/2D

/4

43-48"

D/5

D/8

E/5

D/4

E/2-1/2

E/4

D/5

D/4

E/5

D/4

E/2-1/2

E/2

D/5

D/4

D/2-1/2D

/4

49-54"

D/5

D/4

E/5

E/4

F/2-1/2

F/2

D/5

D/4

E/2-1/2

E/4

F/2-1/2

F/2

D/5

D/4

55-60"

E/5

E/4

F/5

F/4

G/2-1/2

G/2

E/5

E/4

F/2-1/2

F/4

E/2-1/2

E/4

61-72"

F/5

F/4

G/2-1/2

G/4

H/2-1/2

H/2

F/2-1/2

F/4

73-84"

H/5

G/4

G/2-1/2

G/4

85-96"

H/2-1/2H

/4

97"up

Note:FlatslipsanddrivesmaybebackedwithstiffenersfromTableNo.6-

2-Jand

therebyqualifiedforthistable.WherethesuperscriptDoccurs,t

heflatdriveis

acceptedasClassA.SeeTableN

o.6-2-K.

NotAllowed

Standingreinf

orcementisnotrequiredonduct

sizesabovethisheavyline.Flatslipsanddrivesor

anotherchoice

maybeused.

Flatslipsanddrives

mustnotbeles

sthanonegaugebelowductgauge

andnotlesstha

n24gauge.

Thisnumberisthe

spacingintervalbetweenreinforcements,infeet.

Thisletterdenotes

thetypeofreinforcementtobeselectedfromjointTables6-2-I,

6-2-J,or6-2-K.

NotRequired

watergaugex248.8=Pa

inchesx25.4=mm


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289

Standingreinforcementisnotrequiredonduct

sizesabovethisheavyline.Flatslipsand

drivesor

anotherchoicemaybeused.

Flatslipsa

nddrives

mustnotbelessthanonegaugebelowd

uctgauge

andnotlessthan24gauge.

Thisnumberisthespacingintervalbetweenreinforcements

,infeet.

Thisletterdenot

esthetypeofreinforcementtobeselectedf

romjointTablesNos.

6-2-I,

6-2-Jor6-2

-K.

NotRequired

watergaugex248.8=Pa

inchesx25.4=mm

TABLE6-2-H

RectangularDuctTransverseReinforcemen

tforDuctMaterialThicknessesfrom

0.0

58"(16ga.)

(1.4

7mm

)to0

.036"(20ga.)

(0.9

1mm)

PressureClass

1/2"

1/2"

1"

1"

2"

2"

1/2"

1/2"

1"

1"

2"

2"

1/2"

1/2"

1"

1"

2"

2"

(WaterGauge)

DuctThickness

0.0

58"

0.0

58"

0.058"

0.0

58"

0.0

58"

0.0

58"

0.047"

0.0

47"

0.047"

0.047

0.0

47"

0.0

47"

0.036"

0.036"

0.0

36"

0.0

36"

0.0

36"

0.036"

Inches(Gauge)

(16)

(16)

(16)

(16)

(16)

(16)

(18)

(18)

(18)

(18)

(18)

(18)

(20)

(20)

(20)

(20)

(20)

(20)

DuctDimensions

7"dn.

8-10"

11,1

2"

13,1

4"

15,1

6"

17,1

8"

19,2

0"

B/10

B/8

21,2

2"

B

/10

B/8

A/10

A/8

B/10

B/8

23,2

4"

C

/10

C/8

B/10

B/8

B/10

C/8

25,2

6"

C/10

C/8

C

/10

C/8

B/10

B/8

C/10

C/8

27,2

8"

C/10

C/8

C/10

C/8

C

/10

C/8

B/10

B/8

C/10

C/8

C/5

C/8

29,3

0"

D/10

D/8

C/10

C/8

D

/10

D/8

B/10

B/8

C/10

C/8

C/5

D/8

31-36"

D/10

D/8

E/10

E/8

C/10

C/8

D/10

D/8

D

/5

E/8

C/10

C/8

D/10

D/8

D/5

D/4

37-42"

D/10

D/8

E/10

E/8

E/5

E/8

D/10

D/8

E/10

D/8

E/5

E/4

D/10

D/8

D/5

D/8

E/5

E/4

43-48"

E/10

D/8

F/10

F/8

F/5

G/8

E/10

D/8

E/5

E/8

F/5

E/4

E/10

D/8

E/5

D/4

F/5

E/4

49-54"

E/10

E/8

G/10

F/8

G/5

F/4

E/10

E/8

E/5

F/8

G

/5

F/4

D/5

E/8

E/5

E/4

F/2-1/2

F/4

55-60"

F/10

F/8

F/5

G/8

H/5

G/4

F/10

F/8

F/5

G/8

H

/5

G/4

E/5

F/8

F/5

F/4

G/2-1/2

G/4

61-72"

H/10

G/8

H/5

G/4

I/5

H/4

F/5

G/8

H/5

G/4

H/

2-1/2

H/4

F/5

F/4

G/2-1/2

G/4H/2-1/2

H/2

73-84"

H/5

H/8

I/5

H/4

I/2-1/2

J/4

H/5

G/4

I/5

H/4

I/2-1/2

J/4

H/5

G/4

H/2-1/2

H/4I/2-1/2

I/2

85-96"

H/5

I/8

J/5

I/4

J/2-1/2

K/4

H/5

H/4

I/2-1/2

I/4

J/2-1/2

J/2

H/5

H/4

I/2-1/2

I/2

J/2-1/2

J/2

97"up

H/5

H/4

J/2-1/2

J/2

K/2-1/2

K/2

H/5

H/4

J/2-1/2

J/2

K/2-1/2

K/2

Note:FlatslipsanddrivesmaybebackedwithstiffenersfromTableNo.

6-2-Jand

therebyqualifiedforthistable.


8/18


290


H x TWT

H x TWT

H x TWT

H x TWT

H x T + hWT

EI* (x 25.4 for mm)LF

(x 25.4 for mm)LF

(x 25.4 for mm)LF

(x 25.4 for mm)LF

(x 25.4 for mm)LF

A 0.5 1/2 x 0.019" 0.5

(1/2 x 26 ga.)

B 1.0 1-1/8 x 0.019" 0.5 1/2 x 0.030" 0.7

(1-1/8 x 26 ga.) Not given (1/2 x 22 ga.)

C 2.5 1-1/8 x 0.030" 0.8 1 x 0.019" 0.6 1 x 0.019" 0.6

(1-1/8 x 22 ga.) (1 x 26 ga.) 0.6 (1 x 26 ga.) 0.6 Not given

D 0.5 Not given 1 x 0.024" 0.7 1 x 0.024" 0.7 1-1/8 x 0.019" 0.7(1 x 24 ga.) (1 x 24 ga.) (1-1/8 x 26 ga.)

E 10 1-1/8 x 0.036" 0.9 Not given 1-1/8 x 0.047" 1.4(1-1/8 x 20 ga.) (1-1/8 x 18 ga.)

w = 3/16" Not given

F 15 1-5/8 x 0.030" 1.0 1-1/2 x 0.024" 1.0 1-1/2 x 0.024" 1.5

(1-5/8 x 22 ga.) (1-1/2 x 24 ga.) (1-1/2 x 24 ga.)

w = 3/16" 1-1/2 x 1/8 bar 1-1/2 x 1/8 bar

G 25 1-5/8 x 0.047" 1.5 1-1/2 x 0.047" 1.7 1-1/2 x 0.030" 1.6

(1-5/8 x 18 ga.) (1-1/2 x 18 ga.) (1-1/2 x 22 ga.)

w = 3/16" 1-1/2 x 1/8 bar

H 50 Not given Not given 1-1/2 x 0.036" 2.9(1-1/2 x 20 ga.)

1-1/2 x 1-1/2 x 3/16

I 75 2 x 0.036" 2.9

(2 x 20 ga.)

2 x 2 x 1/8

J 100 2 x 0.036"

(2 x 20 ga.)

2 x 2 x 3/16

K 150 Not given

L 200

MinimumRigidity

Class

T-2STANDINGDRIVE SLIP

T-10STANDING S

T-11STANDING S

T-12STANDING S

STANDING S(ANGLE REINFORCED)

T-14

(x 1.488for kg/m)

(x 1.488for kg/m)

(x 1.488for kg/m)

(x 1.488for kg/m)

(x 1.488for kg/m)

Note:

* Nominal EI is number listed times 105.

TABLE 6-2-1

Transverse Joint Reinforcement for Tables 6-2-G and 6-2-H

STANDING S(BAR REINFORCED)

T-13


9/18

LOCK T,WT WT WT WT

EI* H DUCT T, hLF

H x T ULF

H x TLF

H x TLF

(x 25.4 for mm) (x 1.488 (x 25.4 for mm) (x 1.488 (x 25.4 for mm) (x 1.488 (x 25.4 for mm) (x 1.488

for kg/m) for kg/m) for kg/m) for kg/m)

A 0.5

B 1.0 3/4 x 0.019" 0.024" 0.4(26 ga.) (24 ga.)

C 2.5 T-17 0.019" (26 ga.) lock 0.6 1 x 0.024" 0.024" 0.5 1 x 0.024" 1.01" on 0.019" (26 ga.) (24 ga.) (24 ga.) (24 ga.)

D 5.0 T-17 0.024" (24 ga.) lock 0.7 1 x 0.030" 0.030" 0.6 1 x 0.030" 1.01" on 0.024" (24 ga.) (22 ga.) (22 ga.) (22 ga.)

E 10 T-18 0.030" (22 ga.) lock 1.4 1-1/2 x 0.024" 0.030" 0.8 two 1.7 1 x 0.058" (16 ga.) 1.01" 1 x 1/8 bar (24 ga.) (22 ga.) 1 x 1/8 1-1/2 x 0.024" (24 ga.)

F 15 T-17 0.030" (22 ga.) lock 1.0 1-1/2 x 0.036" 0.036" 1.0 1-1/2 x 0.030" (22 ga.) 1.01-1/2" (20 ga.) (20 ga.) 1-1/2 x 0.036" (20 ga.) 1.0

G 25 T-18 0.030" (22 ga.) lock 1.6 two 2.1 1-1/2 x 0.047" 1.51-1/2" 1-1/2 x 1/8 bar 1-1/4 x 1/8 (18 ga.)

H 50 T-19 0.036" (20 ga.) lock 2.9 2 x 0.058" 0.036" 1.5 two 2.6 2 x 0.047" 1.51-1/2" 1-1/2 x 3/16 angle (16 ga.) (20 ga.) 1-1/2 x 1/8 (18 ga.)

I 75 T-10 0.036" (20 ga.) lock 2.8 2 x 0.058" two* 2 x 0.058" 2.01-1/2" 2 x 1/8 angle (16 ga.) 1-1/2 x 3/16 3.7 (16 ga.)

*

J 100 T-19 0.036" (20 ga.) lock 3.5 two* 2 x 0.047"1-1/2" 2 x 3/16 angle 1-1/2 x 1/4 4.7 (18 ga.)

K 150 T-19 0.036" (20 ga.) lock 4.2 two* With

1-1/2" 2-1/2 x 3/16 angle 2 x 3/16 4.9 tie rods

L 200 Not given two*2 x 1/4 6.5


291

MinimumRigidity

Class

TABLE 6-2-I continued

Note:

* Nominal EI is number listed times 105.

BAR REINFORCEDPOCKET LOCK

T-18

POCKET LOCKT-17

ANGLE REINFORCEDPOCKET LOCK

T-19

T-10CAPPED FLANGE

T-22COMPANION

ANGLES

T-23FLANGED


10/18


292


Duct Inches 0.019" to 0.030" 0.036" 0.047" 0.058"

Thickness (Gauge) (26 to 22) (20) (18) (16)

Minimum Flat Slip 0.024" (24) 0.030" (22) 0.036" (20) 0.047" (18)and Drive Gauge

By themselves, flat-type slip connections and lap joints do not qualify asreinforcement. When backed by a stiffener from Table 6-2-J, the reinforcement isgraded by the stiffener. See exception for joint T-1 in Table 6-2-K. T-5, T-6, and T-7 arerestricted to 2" W.G. maximum service pressure.

TABLE 6-2-I continued


11/18


293

TABLE 6-2-JIntermediate Reinforcement

H x T (MIN) WT H x B x T (MIN) WT H x B x D x T WT H x B x D x T (MIN) WTLF LF LF LF

E1* (x 25.4 for mm) (x 25.4 for mm) (x 25.4 for mm) (x 25.4 for mm)(x 1.488 (x 1.488 (x 1.488 (x 1.488


A 0.5

B 1.0 3/4 x 1/2 x 0.036" 0.28(20 ga.)

C 2.5 1 x 0.047" (18 ga.) 0.34 3/4 x 1/2 x 0.047 0.36 3/4 x 3 x 0.047" 0.81

1 x 0.058" (16 ga.) 0.44 (18 ga.) (18 ga.)

3/4 x 1/8 0.59

D 5.0 1-1/4 x 0.047" 1 x 3/4 x 0.036" 0.35 1-1/8 x 3-1/4 x 0.047" 1.0

(18 ga.) 0.45 (20 ga.) (18 ga.)

1 x 1/8 0.80 1 x 3 x 0.047" (18 ga.)

1-1/4 x 0.090 0.80 1 x 3/4 x 0.090 0.78

E 10 1-1/2 x 0.058" 0.66 1-1/2 x 3/4 x 0.036" 0.41 0.7 1 x 2 x 1/8 1.6

(16 ga.) (20 ga.)

1-1/2 x 1/8** 1.23 1 x 3/4 x 1/8 1.03 1-1/2 x 3/4 x 5/8 x 0.036" (20 ga.) 0.7 1-1/4 x 3-1/2 x 0.058" (16 ga.) 1.32

F 15 1-1/2 x 3/4 x 0.047" 0.54 1-1/2 x 1-1/2 x 3/4 x 0.036"(20ga.) 1.1 1-1/8 x 3 x 1/8 2.1(18 ga.)

1-1/2 x 3/16 0.96 1-1/2 x 3/4 x 1/8 1.23 1-1/2 x 3/4 x 5/8 x 0.058" (16 ga.) 0.82

G 25 2 x 1-1/8 x 0.036" 0.6 1-1/2 x 1-1/2 x 3/4 x 0.047" (18 ga.) 1.1

(20 ga.) 2 x 1 x 3/4 x 0.036" (20 ga.) 0.90

2 x 1-1/8 x 0.058" 0.94 1-1/2 x 3/4 x 5/8 x 1/8 2.1 1.4 x 3 4.1H 50 2 x 1/8 1.65 (16 ga.) 1-1/2 x 1-1/2 x 3/4 x 0.090 1.9

2 x 1 x 3/4 x 0.036" (20 ga.) 1.2

2 x 3/16 2.44 2 x 1-1/8 x .090 1.33 2 x 1 x 3/4 x .090 2.03 2 x 2 x 1/8 2.4

I 75 2-1/2 x 2 x 3/4 x 0.058" 1.88 1.5 x 3 5.0

(16 ga.)2 x 1-1/8 x 1/8

J 100 2 x 1/4 3.2 3 x 1-1/8 x 0.058" 1.74 2 x 1 x 3/4 x 1/8 2.63 1.6 x 4 5.4

2-1/2 x 1/8 2.1 (16 ga.) 1.2 2-1/2 x 2 x 3/4 x 0.090 2.67

2-1/2 x 2 x 3/4 x 1/8 3.57

K 150 2-1/2 x 3/16 3.1 3 x 1-1/8 x 0.090 1.64 3 x 1-1/2 x 3/4 x 0.058" 2.0

(16 ga.) Not given

L 200 2-1/2 x 1/4 4.1 3 x 1-1/8 x 1/8 2.15 3 x 1-1/2 x 3/4 x 0.090 2.82

ANGLE ZEE HAT SECTION CHANNELMinimum

RigidityClass

Notes:

*Nominal El is number listed times 105.** See tie rod options.


12/18

WT WT WT WT

EI* HS x T LF HS H x H x T LF HS H x H x T LF HS x T LF(x 25.4 for mm) (x 1.488 (x 25.4 for mm) (x 1.488 (x 25.4 for mm) (x 1.488 (x 25.4 for mm) (x 1.488


A 0.5 1/2 x 0.024" 0.2 1/2 x 0.030" 0.1(24 ga.) (22 ga.)

B 1.0 3/4 x 0.024" 0.3 1/2 x 0.058" (16 ga.) 0.2(24 ga.) 3/4 x 0.030" (22 ga.) 0.2

C 2.5 1 x 0.024" 0.5 3/4 x 0.047" (18 ga.) 0.3(24 ga.) 1 x 0.030 (22 ga.)

D 5.0 3/4 x 0.058" (16 ga.) 0.3 1" 1 x 1 x 0.058" 1.0 1 x 0.047" (18 ga.) 0.41 x 0.036" (20 ga.) 0.5 (16 ga.) 1-1/4 x 0.030" (22 ga.) 0.3

E 10 1 x 0.058" (16 ga.) 0.7 1" 1 x 1 x 1/8 1.4 1" 1 x 1 x 0.058" 1.0 1-1/4 x 0.047" (18 ga.) 0.51-1/2 x 0.024" (24 ga.) 0.7 (16 ga.) 1-1/2 x 0.030" (22 ga.) 0.4

F 15 1-1/2 x 0.036" 0.7 1-1/2" 1-1/2 x 1-1/2 x 0.058" 1.8 1-1/4" 1-1/4 x 1-1/4 x 0.058" 1.7 1-1/4 x 0.058" (16 ga.) 0.6

(20 ga.) (16 ga.) (16 ga.) 1-1/2 x 0.036" (20 ga.) 0.4

1-1/2 x 0.047" 0.8 1-1/2" 1-1/2 x 1-1/2 x 1/8 1-1/2"1-1/2 x 1-1/2 x 1/8 1-1/2 x 0.058" (16 ga.) 0.7G 25 (18 ga.) 1-1/2" 2 x 2 x 0.058" 2.0 2.4

(16 ga.)

See T-16 1-1/2" 2 x 2 x 1/8* 2.7 1-1/2"1-1/2 x 1-1/2 x 3/16 2.8 See T-21aH 50 and tie rod 1-1/2" 2 x 2 x 0.058" 2.0 and tie rod

options (16 ga.) optionsTable No. 10-2-Q

I 75 1-1/2" 2 x 2 x 1/8* 2.7

J 100 1-1/2" 2 x 2 x 3/16* 3.5 1-1/2" 2 x 2 x 3/16* 3.5

K 150 1-1/2" 2-1/2 x 2-1/2 x 3/16* 4.1

L 200 1-1/2" 2-1/2 x 2-1/2 x 1/4 5.3 1-1/2" 2-1/2 x 2-1/2 x 3/16* 4.1


294


TABLE 6-2-KTransverse Joint Replacement for Tables Nos. 6-2-G, 2-H, 2-L, 2-N, and 2-O

Note:

*Nominal El is number listed times 105.

MinimumRigidity

Class26 TO 22 GA. DUCT

STANDING SEAM OR WELDED FLANGE REINFORCED

20 TO 16 GA. DUCT

T-15STANDING SEAM

T-21aT-16T-21

WELDED FLANGE


13/18

TABLE NO. 6-2-L Rectangular Duct Reinforcement

Notes:

1. Reinforcement class refers to transverse joint or intermediate members having stiffness and other characteristics indicated in tables.2. Joint spacing is unrestricted.3. Reinforcement is evaluated for each duct side separately. When required on four sides, corners shall be tied. When required on two

sides, corners shall be tied with rods or angles at the ends on 4 inch (995 Pa), 6 inch (1493 Pa), and 10 inch (2488 Pa) pressure classes.4. The same gauge of metal shall be used on all four sides of a cross-section.

3" W.G. (746 Pa)

Static 0.058" 0.047" 0.036" 0.030" 0.024"

Pos. or Neg. (16 gauge) (18 gauge) (20 gauge) (22 gauge) (24 gauge)

(x 25.4 for mm) (x 304.8 for mm)

Duct Dimension Minimum Class Maximum Spacing

10" down Not required Not required Not required Not required Not required11" to 12" A @ 8'13" to 14" A @ 8' A @ 5'15" to 16" A @ 8' A @ 8' A @ 5'17" to 18" A @ 8' A @ 8' A @ 5'

19" to 20" B @ 10' B @ 8' A @ 5' A @ 5'21" to 22" C @ 10' B @ 8' B @ 5' B @ 5'23" to 24" C @ 10' B @ 5' B @ 5' B @ 5'25" to 26" D @ 10' D @ 10' C @ 5' C @ 5' C @ 5'27" to 28" D @ 10' D @ 10' C @ 5' C @ 5' C @ 4'29" to 30" D @ 10' D @ 8' C @ 5' C @ 5' C @ 4'31" to 36" E @ 8' E @ 5' E @ 5' D @ 4' D @ 4'

37" to 42" E @ 5' E @ 5' E @ 5' E @4' E @ 3'43" to 48" G @ 5' G @ 5' F @ 4' E @ 3' E @ 2-1/2'49" to 54" H @ 5' H @ 5' G @ 3' G @ 3' E @ 2-1/2'55" to 60" H @ 5' H @ 4' G @ 3' G @ 2-1/2' G @ 2-1/2'61" to 72" I @ 4' H @ 3' H @ 4' H @ 2-1/2' F @ 2'*73" to 84" J @ 3' J @ 3' J @ 2-1/2' I @ 2'85" to 96" L @ 3' K @ 2-1/2' J @ 2' G @2-1/2'*Over 96" H @ 2-1/2'*

TABLE 6-2-K continued

Note:

Where Table Nos. 6-2-G, H, L, M and N require Class A reinforcement, joint T-1 is acceptable as Class A within these parameters and

without supplemental reinforcement from Table No. 6-2-J.


295

Maximum Allowable Duct Maximum ReinforcementStatic Width Dimension Spacing Interval

Pressure (Pa) Inches (mm) Feet (mm)

1/2" W.G. (124) 20 (508) 10 (3,048)1" W.G. (249) 20 (508) 8 (2,438)

14 (356) 10 (3,048)

2" W.G. (498) 20 (508) 5 (1,524)18 (457) 8 (2,438)

3" W.G. (764) 18 (457) 8 (2,438)

4" W.G. (995) 16 (406) 5 (1,524)12 (305) 8 (2,438)

6" W.G. (1493) 12 (305) 5 (1,524)


14/18


296


TABLE NO.6-2-MRectangular Duct Reinforcement

Notes:

1. Reinforcement class refers to transverse joint or intermediate members having stiffness and other characteristics indicated in tables.2. Joint spacing is unrestricted.

3. Reinforcement is evaluated for each duct side separately. When required on four sides, corners shall be tied. When required on twosides, corners shall be tied with rods or angles at the ends on 4 inch (995 Pa), 6 inch (1493 Pa), and 10 inch (2488 Pa) pressure classes.

4. The same gauge of metal shall be used on all four sides of a cross-section.5. *Plus tie rods at 48 inches (1219 mm) maximum along joints and intermediates.

Tie rod sizes: 1/4 inch (6.4 mm) diameter for 36 inch (914 mm) length or less; 3/8 inch (9.5 mm) diameter for over 36 inches (914 mm).Space at even divisions of duct width.

4" W.G.(995 Pa)Static 0.058" 0.047" 0.036" 0.030" 0.024"

Pos. or Neg. (16 gauge) (18 gauge) (20 gauge) (22 gauge) (24 gauge)(x 25.4 for mm) (x 304.8 for mm)


8" down Not required Not required Not required Not required Not required9" to 10" A @ 5'

11" to 12" A @ 10' A @ 5'13" to 14" A @ 10' A @ 8' A @ 5'15" to 16" A @ 10' A @ 5' A @ 5'17" to 18" B @ 10' B @ 8' A @ 5' A @ 5'19" to 20" C @ 10' C @ 10' B @ 8' B @ 5' B @ 5'21" to 22" C @ 10' C @ 10' B @ 5' B @ 5' B @ 4'23" to 24" D @ 10' D @ 10' C @ 5' C @ 5' C @ 4'25" to 26" D @ 10' D @ 10' C @ 5' C @ 5' C @ 4'27" to 28" E @ 10' E @ 8' D @ 5' D @ 5' D @ 4'

29" to 30" E @ 10' E @ 8' D @ 5' D @ 5' D @ 4'31" to 36" E @ 5' E @ 5' E @ 5' E @4' D @ 3'37" to 42" F @ 5' F @ 5' F @ 4' E @ 3' E @ 2-1/2'43" to 48" G @ 5' G @ 5' F @ 3' F @ 3' E @ 2'49" to 54" H @ 5' H @ 4' G @ 3' G @ 2-1/2' F @ 2'55" to 60" I @ 5' H @ 3' H @ 3' H@ 2-1/2' G @ 2'61" to 72" I @ 3' I @ 3' I @ 2-1/2' H @ 2'73" to 84" K @ 3' J @ 2-1/2' J @ 2'85" to 96" L @ 2-1/2' K @ 2' K @ 2'Over 96" H @ 2-1/2'*


15/18


16/18

TABLE 6-2-ORectangular Duct Reinforcement

Notes:

1. Reinforcement class refers to transverse joint or intermediate members having stiffness and other characteristics indicated in tables.2. Joint spacing is unrestricted.3. Reinforcement is evaluated for each duct side separately. When required on four sides, corners shall be tied. When required on two

sides, corners shall be tied with rods or angles at the ends on 4 inch (995 Pa), 6 inch (1493 Pa), and 10 inch (2488 Pa) pressure classes.4. The same gauge of metal shall be used on all four sides of a cross-section.5. *Plus tie rods at 48 inches (1,219 mm) maximum along joints and intermediates.

Tie rod sizes:1/4 inch (9.5 mm) diameter for 36 inch (914 mm) length or less; 3/8 inch (9.5 mm) diameter for over 36 inches (914 mm).Space at even divisions of duct width.


298


10" W.G. (2488 Pa)Static 0.058" 0.047" 0.036" 0.030" 0.024"

Positive (16 gauge) (18 gauge) (20 gauge) (22 gauge) (24 gauge)(x 25.4 for mm) (x 304.8 for mm)


8" down Not required Not required Not required Not required Not required9" to 10" A @ 5 A @ 5' A @ 4'

11" to 12" A @ 8' A @ 5' A @ 5' A @ 4'13" to 14" B @ 8' B @ 8' A @ 5' A @ 4' A @ 3'15" to 16" B @ 8' B @ 5' B @ 5' B @ 4' A @ 3'17" to 18" C @ 8' C @ 5' C @ 5' B @ 4' B @ 3'19" to 20" D @ 8' C @ 5' C @ 4' B @ 3' B @ 3'21" to 22" C @ 5' C @ 5' C @ 4' C @ 3' C @ 3'23" to 24" D @ 5' D @ 5' D @ 4' C @ 3' C @ 3'25" to 26" D @ 5' D @ 5' D @ 4' D @ 3' C @ 2-1/2'27" to 28" E @ 5' E @ 5' D @ 4' D @ 3' D @ 2-1/2'29" to 30" E @ 5' E @ 4' D @ 3' D @ 3' D @ 2-1/2'

31" to 36" F @ 5' F @ 4' F @ 3' E @ 2-1/2' E @ 2'37" to 42" H @ 4' G @ 3' G @ 2-1/2' F @ 2'43" to 48" H @ 3' H @ 2-1/2' G @ 2' G @ 2'49" to 54" I @ 3' H @ 2-1/2'' H @ 2'55" to 60" J @ 3' I @ 2-1/2' I @ 2'61" to 72" K @ 2-1/2' K @ 273" to 84" H @ 2'85" to 96" H @ 2'*Over 96" H @ 2'*


17/18


299

TABLE 6-2-P-1Rectangular Aluminum Duct

Adapted from 3" W.G. (746 Pa) or Lower Steel Construction TablesAmend Tables 6-2-G, 6-2-H, and 6-2-L by using equivalent thicknesses from this table.

*Note: The aluminum reference in the table is Alloy 3003-H14. If calculations are performed, the following allowable stresses shall be used:tension or compression, 10,000 psi (68.9 MPa); shear, 6,000 psi (41.4 MPa); bearing, 16,000 psi (110 MPa). Unstiffened flanges shall havestress reduced for the specified width-to-thickness ratio.

Table 6-2-P-2Dimension Adjustments

**Calculate an Ix = 3 x that used for steel.

TABLE NO. 6-2-P-3Reinforcements

***Alloy 6061-T6 strength normally

Notes for Tables 6-2-P-1, P-2, and P-3:

1. For Tables 6-2-G, 6-2-H, and 6-2-L, use equivalent thickness from Table 6-2-P-1 for required thickness of aluminum stock.2. For Tables 6-2-I and 6-2-K: 2a) A connector not using angles or bar stock shall have its thickness increased per Table 6-2-P-1 and its

dimensions increased per Table 6-P-2. 2b) A connector using angles or bar stock shall have its aluminum thickness increased per Table6-2-P-1 and shall use either aluminum stock or galvanized stock from Table 6-2-P-3.

3. Table 6-2-J: Galvanized steel members of dimensions given may be used, or aluminum members having thickness and dimensionconforming to Table 6-2-P-3 may be used. Other suitable aluminum shapes having a moment of inertia three times that of steel may beused.

4. Button-punch snaplock seams shall not be used in fabricating aluminum rectangular duct.

Equivalent Aluminum***Steel Angle Size, Inches Code Angle Size, Inches Steel Bar Aluminum Bar***

1 x 1 x 0.058 (16 ga.) C 1-1/4 x 1-1/4 x 1/8 1 x 1/8 1-1/2 x 1/8 or1-1/4 x 3/16

1 x 1 x 1/8 D 1-1/2 x 1-1/2 x 1/8 1-1/2 x 1/8 1-1/2 x 3/8 or2 x 3/16

1-1/4 x 1-1/4 x 1/8 E 1-3/4 x 1-3/4 x 1/8

1-1/2 x 1-1/2 x 1/8 F 2 x 2 x 3/16 or2-1/2 x 2-1/2 x 1/8

1-1/2 x 1-1/2 x 3/16 G 2 x 2 x 1/4 or2-1/2 x 2-1/2 x 1/8

2 x 2 x 1/8 H 2-1/2 x 2-1/2 x 3/16

2 x 2 x 3/16 I 2-1/2 x 2-1/2 x 5/16 or3 x 3 x 1/4

2 x 2 x 1/4 J 2-1/2 x 2-1/2 x 3/8 or3 x 3 x 1/4

2-1/2 x 2-1/2 x 3/16 K 3 x 3 x 3/8 or3-1/2 x 3-1/2 x 1/4

Galvanized rigidity class A B C D E F G H I J K L

Aluminum dimension per galvanized class C D E F H H I K ** ** ** **

Galv. Steel Thickness, Inches 0.016 0.019 0.024 0.030 0.036 0.047 0.058(Gauge) (28) (26) (24) (22) (20) (18) (16)

Min. Aluminum Equivalent* 0.023 0.027 0.035 0.043 0.052 0.068 0.084Commercial Size 0.025 0.032 0.040 0.050 0.064 0.071 0.090

Aluminum weight: 171.1 pounds per cubic foot (2,738 kg/m3)

inches x 25.4 = mm


18/18

Tie Rod Installations.

In Tables 6-2-G, H, L, M, N, and O, duct sizes overforty-eight (48) inches (1,219 mm) have a tie rodoptional construction for positive pressures.

TABLE 6-2-Q

Intermediate Tie Rods at Reinforcement

(Between Joints)

Duct Table Reinforcement Reinforcement Grade

Width Grade for Tie Rod Option

49" t o 96" G, H , I, o rJ 1-1/2" x 1/2" x 1/8" angle

with tie rod at center

73" to K or L 1-1/2" x 1-1/2" x 3/16"

angle with tierodat center

97" up H with tie rod 2" x 2" x 1/8"

angle with tie rod at 60"

maximum intervals

Tie Rods at Joints.

The direct attachment of the tie rod by brazing orwelding to a vertical leg of the joint is allowed for

joints T-15, T-20, T-22, and T-23.

The attachment of a tie rod to an angle thatreinforces a joint is allowed for joints T-4, T-8, T-9, T-15, T-16, T-19, and T-21. The angle shall meet therequirements for t ie-rodded intermediatereinforcement.

The attachment of two tie rods or tie straps to

the duct wall by welding or bolting within one (1)inch (25 mm) of both sides of joints T-15, T-20, T-21and T-23 is allowed.

Additional General Requirements.

Ties shall be attached in such a manner that they willnot loosen or detach with normal operating pressurefluctuations in the duct. When ties are to be welded tothe duct wall, the rod or strap shall have a 90 degree(1.57 rad) bend with 5/8 inch (15.9 mm) minimumextension beyond the bend. The extension of the rodshall be welded to the duct. The strap shall be weldedto the duct at the 90 degree (1.57 rad) bend.

Holes made in the duct wall for tie rod passageshall be the minimum size.

Tie rods shall be galvanized steel of 1/4 inch (6.4mm) minimum diameter if thirty-six (36) inch (914mm) length or less and 3/8 inch (9.5 mm) minimumdiameter for greater length.

Tie straps shall be one (1) inch by 1/8 inch (25.4mm by 3.2 mm) galvanized steel minimum, and thesmallest edge shall face the airflow direction.

Ties shall be spaced at even intervals of ductwidth not exceeding sixty (60) inches (1,524 mm).

The use of ties does not void the need to attachreinforcements to the duct wall. However, when tieso cc ur o ut si de o f t he d uc t, a s o n t wo -s id ereinforcements at four (4) inch w.g. (995 Pa) and

over, the attachment within two (2) inches (50 mm)of the corner is not required.

When ties occur in two directions in the samevicinity, they shall either be prevented fromcontacting or shall be in permanent contact.

Ties may be used as components of thesuspension system for ducts over ninety-six (96) inch(2,438 mm) width, provided that the hanger load isd ir ec t ly t ra ns mi tt ed t o a t ra pe ze o r d uc treinforcement member beneath the duct.

The construction of ducts of widths greater thanninety-six (96) inches (2,438 mm) requires the use oftie rods on Grade H joints and intermediates (2" x 2"

x 1/8") (51 mm by 51 mm by 3.2 mm) at intervals notexceeding sixty (60) inches (1,524 mm) in thetransverse direction. For ten (10") w.g. (2,488 Pa),sixteen (16) gauge (1.47 mm) ducts with two (2) feet(610 mm) reinforcement spacing is required;eighteen (18) gauge (1.19 mm) duct is required atlower pressures with spacings of two (2) feet (610mm) at six (6") w.g. (1,493 Pa); 2-1/2 feet (762 mm) atone (1") to four (4") w.g. (249 Pa to 995 Pa); and five(5) feet (1,524 mm) at 1/2" w.g (124 Pa).


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Uniform Mechanical Code- 2009 Appendix a 6-2

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Transcript of Uniform Mechanical Code- 2009 Appendix a 6-2