4.12.743    TABLES

(1)  Table A - Rate of Discharge.

 

     TABLE A - RATE OF DISCHARGE

 

Minimum required rate of discharge in cubic feet per minute (CFM)  of air for safety relief valves. Discharge measured at 60 degrees F and atmospheric pressure (14.7 pounds per square inch)  .

 

Surface

Area

Sq. Ft.

  CFM

Surface

Area

Sq. Ft.

   CFM

Surface

Area

Sq. Ft

   CFM

  20

   258

185 

1,600

   900

  5,850

  25

   310

190

1,640

   950

  6,120

  30

   360

195

1,670

1,000

  6,380

  35

   408

200

1,710

1,050

  6,640

  40

   455

210

1,780

1,100

  6,900

  45

   501

220

1,850

1,150

  7,160

  50

   547

230

1,920

1,200

  7,410

  55

   591

240

1,980

1,250

  7,660

  60

   635

250

2,050

1,300

  7,910

  65

   678

260

2,120

1,350

  8,160

  70

   720

270

2,180

1,400

  8,410

  75

   762

280

2,250

1,450

  8,650

  80

   804

290

2,320

1,500

  8,900

  85

   845

300

2,380

1,550

  9,140

  90

   885

310

2,450 

1,600

  9,380

  95

   925

320

2,510

1,650

  9,620

100

   965

330

2,570

1,700

  9,860

105

1,010

340

2,640

1,750

10,090

110

1,050

350

2,700

1,800

10,330

115

1,090

360

2,760

1,850

10,560

120

1,120

370

2,830

1,900

10,800

125

1,160

380

2,890

1,950

11,030

130

1,200

390

2,950

2,000

11,260

135

1,240

400

3,010

2,050

11,490

140

1,280

450

3,320

2,100

11,720

145

1,310

500

3,620

2,150

11,950

150

1,350

550

3,910

2,200

12,180

155

1,390

600

4,200

2,250

12,400

160

1,420

650

4,480

2,300

12,630

165

1,460

700

4,760

2,350

12,850

170

1,500

750

5,040

2,400

13,080

175

1,530 

800

5,300

2,450

13,300

180

1,570

850

5,590

2,500

13,520

Surface area = Total outside surface area of container in square feet. When the surface area is not stamped on the name plate or when the marking is not legible, the area can be calculated by using one of the following formulas:

 

(a) Cylindrical container with hemispherical heads area = (overall length in feet times outside diameter in feet times 3.1416).
(b) Cylindrical container with semi-ellipsoidal heads. Area = (overall length in feet plus 0.3 outside diameter in feet)  times diameter in feet times 3.1416.
(c) Spherical Container. Area = Outside diameter in
    

Flow Rate SCFM Air = Cubic feet per minute of air required at standard conditions, 60 degrees F and atmospheric pressure (14.7 psia).

 

The rate of discharge may be interpolated for intermediate values of surface area. For container with total outside surface area greater than 2,000 sq. ft., the required flow rate can be calculated using the formula, Flow Rate SCFM Air = 22.11A degrees .82, where A = Outside surface area of the container in square feet.

 

(2)  Table B - Guide for Selection of Materials for Refrigerated Ammonia Storage Tanks.

 

TABLE B - GUIDE FOR SELECTION OF MATERIALS

FOR REFRIGERATED AMMONIA STORAGE TANKS

(a) Materials for shell and bottom for tanks of all design pressures shall have ductility at low temperatures equal to or superior to those listed in Table C.
(b) When austenitic steels or non-ferrous materials are used, the code shall be used as a guide for temperature requirements.
(c) Materials for nozzles, attached flanges, structural members which are in tension, and other such critical elements shall be selected for the design temperature. This selection shall be based on impact test requirements, or on probabilities such as used for the plate materials listed in Table C.

  

 

(3)  Table C - Minimum Material Requirements for Shells and Bottoms of Refrigerated Storage Tanks for Various Temperatures and Thicknesses.

 

TABLE C - MINIMUM MATERIAL REQUIREMENTS FOR SHELLS AND BOTTOMS OF REFRIGERATED STORAGE TANKS FOR VARIOUS TEMPERATURES AND THICKNESSES

 

Design Temperature Thickness Material Spec. Qualifications to be Added to the Basic Specification

65 F to 25 F,
Incl.

(See Note 1)

Up to 1/2", Incl. Any approved steel with specified min.T.S. not exceeding 60,000 psi

None

Over 1/2" to 1", Incl. A-131B (or C)

None

Case 1256

None

A-201 A & B

FGP (Fine Grain Practice)

Over 1" to 1 3/8",
Incl. 
A-131C, Case 1256

None

A-201 A&B

None

FGP

Over 1 3/8" A-131C

Normalized

Case 1256

Normalized

A-201 A & B

FGP, Normalized

Below 25 F to

5 F, Incl.

(See Note 2)

Up to 1/2", Incl.  Case 1256

None

A-201 A & B

 None

Over 1/2" to 1 3/8", Incl. A-131B (to 1" max)

FGP

A-131C

 FGP

Case 1256

FGP

A-201 A & B (to 1" max)

FGP, High Mang.*

A-201 A & B (over 1")

FGP, High Mang., Normalized

Over 1 3/8" A-131C

Normalized

Case 1256

Normalized

A-201 A & B

FGP, High Mang., Normalized

Below -5F to -30F

(See note 3)

Up to 1/2" Incl. Case 1256

FGP

A-201 A & B 

FGP, High Mang.

Over 1/2" to 1 3/8" Incl. A-131B (to 1" max)

FGP, Normalized

A-131C

Normalized

Case 1256

FGP, Normalized

A-201 A & B

FGP, High Mang., Normalized

Over 1 3/8" A-300 Class 1

A-201 A & B Only

*Manganese content of 0.70% to 1.0% is preferred in lieu of usual content of 0.80% maximum.

 

Note 1: The design temperature shall be taken as the lower of the following:

 

(a)  The minimum temperature to which the tank contents will be refrigerated.

(b)  The minimum estimated tank shell temperature due to atmospheric temperatures,

       considering effectiveness of the insulation in keeping shell temperatures above

       expected minimum atmospheric temperature (if expected to be below the

       refrigerated temperature)  .

 

Note 2: For the thickness, temperature category approved steels include all of those listed in the

API 12-C and API 620. Materials for vessels must comply with the requirements of the code and

any additional requirements of the code and any additional requirements of this table. A-131 steel

is not approved by ASME and some code cases have not been approved by local jurisdictions.

All specific materials listed in table are satisfactory for all designs based on API 12-C or API 620.

 

Note 3: For vessels constructed under the code with a design temperature below -20F.,

the impact requirements shall comply with Table B.

 

(4)  Table D - Repair Welding.

 

TABLE D - REPAIR WELDING

 

(a)



All containers, piping and appurtenances which have contained or have been in direct contact with nitrogen fertilizer solutions containing ammonium nitrate must be thoroughly cleaned and washed with water (or steam)  to eliminate all solid ammonium nitrate before welding or torch cutting may be attempted: Extreme caution should be taken before attempting to weld or torch cut any container when. ammonium nitrate could be trapped, for example, in the area between tank shell and a reinforcing plate.
(b)


All containers, piping, and appurtenances which have contained aqua ammonia (ammonium hydroxide)  must be thoroughly vented and thoroughly washed with large quantities of water. After washing, they shall be filled with water to a level higher than area to be welded or repaired.
(c) All containers shall be welded in accordance with the code.
    

(5)  Table E - Safety Pressure Relief Valves.

 

          TABLE E - SAFETY PRESSURE RELIEF VALVES

 

(a)

The rate of discharge shall be stamped on the safety relief valve in cubic feet of air per minute at:
(1)  60 degrees F,
(2)  14.7 pounds per square inch absolute, and
(3)  120 percent of the stamped start-to-discharge setting.
(b)

Safety pressure relief valves in systems utilizing air compressors for the transfer of nitrogen fertilizer solutions shall have a minimum rate of discharge in cubic feet per minute of air of 120 percent of the compressor manufacturer's maximum rated capacity.
(c)


Safety pressure relief valves in systems utilizing pumps for transfer of nitrogen fertilizer solutions shall have a minimum rate of discharge of 120 percent of the liquid inflow rate. This can be computed as follows: Liquid pump maximum rated capacity in GPM times 0.16 equals vapor flow in CFM.
  

History: 80-10-503, MCA; IMP, 80-10-503, MCA; NEW, 1986 MAR p. 1820. Eff. 10/31/86; AMD, 2024 MAR p. 128, Eff. 1/27/24.