Spacing of Welds Around Connections See Figure 3-22 for spacing requirements listed in .1

SECTION 3—DESIGN

3.7 SHELL OPENINGS .1 General

3.7.3 Spacing of Welds Around Connections See Figure 3-22 for spacing requirements listed in .1

through 3.7.3.4.

Note: Additional weld spacing requirements exist in this standard.

Other paragraphs and tables dealing with nozzles and manholes may increase the minimum spacing.

Note: Whenever stress relief or thermal stress relief is used in this standard, it shall mean post-weld heat treatment.

3.7.3.1 For nonstress-relieved welds on shell plates over 12.5 mm (¹/₂ in.) thick, the minimum spacing between penetration connections and adjacent shell-plate joints shall be governed by the following:

a. The outer edge or toe of fillet around a penetration, around the periphery of a thickened insert plate, or around the periphery of a reinforcing plate shall be spaced at least the greater of eight times the weld size or 250 mm (10 in.) from the centerline of any butt-welded shell joints.

b. The welds around the periphery of a thickened insert plate, around a reinforcing insert plate, or around a reinforcing plate shall be spaced at least the greater of eight times the larger weld size or 150 mm (6 in.) from each other.

3.7.3.2 Where stress-relieving of the periphery weld has been performed prior to welding of the adjacent shell joint or where a nonstress-relieved weld is on a shell plate less than or equal to 12.5 mm (¹/₂ in.) thick, the spacing may be reduced to 150 mm (6 in.) from vertical joints or to the greater of 75 mm (3 in.) or 2¹/₂ times the shell thickness from horizontal joints. The spacing between the welds around the periphery of a thickened insert plate or around a reinforcing plate shall be the greater of 75 mm (3 in.) or 2¹/₂ times the shell thickness.

Table 3-5—Dimensions for Bolt Circle Diameter D_b and Cover Plate Diameter D_c for Shell Manholes

Column 1 Column 2 Column 3

Manhole Diameter mm (in.)

Bolt Circle Diameter D_b mm (in.)

Cover Plate Diameter D_c mm (in.) 500 (20) 656 (26¹/₄) 720 (28³/₄) 600 (24) 756 (30¹/₄) 820 (32³/₄) 750 (30) 906 (36¹/₄) 970 (38³/₄) 900 (36) 1056 (42¹/₄) 1120 (44³/₄) Note: See Figure 3-4A.

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Figure 3-4A—Shell Manhole

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500 mm (20") manhole: 635 mm (25³/8") OD × 500 mm (20") ID × 3 mm (¹/8") thickness 600 mm (24") manhole: 735 mm (29³/8") OD × 600 mm (24") ID × 3 mm (¹/8") thickness 750 mm (30") manhole: 885 mm (35³/⁸") OD × 750 mm (30") ID × 3 mm (¹/⁸") thickness 900 mm (36") manhole: 1035 mm (41³/8") OD × 900 mm (36") ID × 3 mm (¹/8") thickness Gasket (see Note 1):

Reinforcing pad shall be shaped to suit tank curvature

Rounded corners

(150 mm [6"] minimum radius)

Arc dimension = W/2 500 mm (20") and 600 mm (24") manhole: 750 mm (30") 750 mm (30") manhole: 900 mm (36") 900 mm (36") manhole: 1050 mm (42") (Increase as necessary for clearance)

t T

See details

125 mm (5") minimum 32 mm (1¹/4")

500 mm (20") and 600 mm (24") shell manholes: twenty-eight 20 mm-diameter (³/4") bolts in 24 mm (⁷/8") holes 750 mm (30") and 900 mm (36") shell manholes: forty-two 20 mm-diameter (³/4") bolts in 24 mm (⁷/8") holes (Bolt holes shall straddle the flange vertical centerline.)

(See Figure 3-4B)

Alternative circular shape (see Note 8)

1 1

230 mm (9")

10 mm-diameter (³/8") rod

75 mm (3")

150 mm (6")

DO/2 (see Note 8)

CL CL

D_b D_p

6 mm (¹/4") C L

One 6 mm (¹/4") telltale hole in reinforcing plate, on horizontal centerline

Symmetrical about

DR/2 (see Note 8) L

See Figure 3-4B

(See Note 7)

See Note 2

(see Note 4) Rounded

corner Manhole ID Uniform, smooth surface

6 mm (¹/4")

Detail a

See Note 2

tn(see Note 4)

tf (see Note 3) Manhole ID Rounded

corners

See Note 5

Detail b tf (see Note 3)

t_f

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,,,

(see Note 8)

Notes:

1. Gasket material shall be specified by the purchaser. See 3.7.5.4.

2. The gasketed face shall be machine finished to provide a minimum gasket-bearing width of 20 mm (³/4 in.).

3. See Table 3-3.

4. See Table 3-4.

5. The size of the weld shall equal the thickness of the thinner member joined.

6. The shell nozzles shown in Table 3-6 may be substituted for manholes.

7. When the shell nozzles shown in Figure 3-5 are used, the minimum centerline heights above the tank bottom given in Table 3-6 are acceptable.

8. For dimensions for D_o, D_R, L, and W, see Table 3-6, Columns 4, 5, and 6.

01 ●

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D (min) O

L and W or D

(see Table 3-6)

OD of insert plate

(See Note 2)

C L

JJNeck bevel should be about 10 degrees Round and grind corner (See Table 3-7)(See Tables 3-6 and 3-7)

C L

T + t (min) Shell

(See Note 2) D (min) O

(See Note 3)A

t (min) 45°

1/3 (T + t)min

(See Note 2)

1/3 (t +T)min (See Table 3-7) T + t (min)A Bottom

45° [10 mm (3/8") maximum][10 mm (3/8") maximum] Radiograph (see 6.1.2.2, Item d)

T + t (min) 1:4 bevel

Alternative bevel Radiograph (see 6.1.2.2, Item d)

45°

C L C L

INSERT-TYPE REINFORCEMENT FOR MANHOLES AND NOZZLES

A Radiograph (see 6.1.2.2, Item d)

1.5 mm (1/16")1.5 mm (1/16") t1:4 bevel

1:4 bevel

(See Tables 3-6 and 3-7)

(See Note 1) Manufacturer’s standard (15 degrees minimum, 35 degrees maximum)

A Round corner if weld <T

(See Table 3-7)(See Table 3-7) A [10 mm (3/8") maximum] NOZZLE

(See Note 1) Manufacturer’s standard

(15 degrees minimum, 35 degrees maximum) L and W (Table 3-6) or D

T or t [40 mm (11/2") maximum]

1.5 mm (1/16") T or t [40 mm (11/2") maximum]

1.5 mm (1/16") Round corner if weld <T

(See Tables 3-6 and 3-7)

Round and grind

Neck bevel should be about 10 degrees (See Table 3-7) MANHOLE OR NOZZLE Alternative neck detail

tn tn

tn 1.5 mm (1/16") Notes: 1.See Table 3-7, Column 3, for the shell cutout, which shall not be less than the outside diameter of the neck plus 13 mm (1/2) inch. 2.Refer to 3.7.3 for minimum spacing of welds at opening connections. 3.The weld size shall be either A (from Table 3-7, based on t ) or tn (minimum neck thickness from Tables 3-4, 3-6, and 3-7), whichever is greater.

4.Other permissible insert details are shown in Figure 3-8 of API Standard 620. The reinforcement area shall conform to 3.7.2. 5.Dimensions and weld sizes that are not shown are the same as those given in Figure 3-4A and Tables 3-4 through 3-8. 6.Details of welding bevels may vary from those shown if agreed to by the purchaser.● Figure3-4B—Details of Shell Manholes and Nozzles

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Figure 3-5—Shell Nozzles (See Tables 3-6, 3-7, and 3-8)

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REINFORCING PLATE

REGULAR-TYPE FLANGED NOZZLES, NPS 3 OR LARGER (Bolt holes shall straddle flange centerlines)

Diamond Circular

Single Flange Special Flange

Detail b One 6 mm (¹/4") telltale hole

in reinforcing plate, on horizontal centerline Bend reinforcing plate to

radius of tank shell Alternative shape for low-type nozzles See Detail a or b for

bottom edge

(See Figure 3-4B) (See Figure 3-4B) (See Figure 3-4B)

(See Figure 3-4B) Arc distance 1

Tank bottom

Victaulic groove or threads

(See Note 1) (See Note 1)

(See Note 1)

(See Note 5) 60°

t / 2 [6 mm (¹/4") minimum]

C Chip

D_O

D_P

D_R D_R

L D_P

D_R/ 2

J J

t T Q

B B H_N

J J

t T

Q Q

J t

T Q

Nozzle CL

Double Flange

T T

t t

Detail a

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LOW-TYPE FLANGED NOZZLES, NPS 3 OR LARGER (Bolt holes shall straddle flange centerlines) Notes:

1. See 3.1.5.7 for information on the size of welds.

2. See 3.8.8 for information on the couplings used in shell nozzles.

3. Nozzles NPS 3 or larger require reinforcement.

4. Details of welding bevels may vary from those shown if agreed to by the purchaser.

5. Shop weld not attached to bottom plate.

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3.7.3.3 The rules in 3.7.3.1 and 3.7.3.2 shall also apply to the bottom-to-shell joint unless, as an alternative, the insert plate or reinforcing plate extends to the bottom-to-shell joint and intersects it at approximately 90 degrees. A minimum distance of 75 mm (3 in.) shall be maintained between the toe of a weld around a nonreinforced penetration (see 3.7.2.1) and the toe of the shell-to-bottom weld.

3.7.3.4 By agreement between the purchaser and the manufacturer, circular shell openings and reinforcing plates (if used) may be located in a horizontal or vertical butt-welded shell joint provided that minimum spacing dimensions are met and a radiographic examination of the welded shell joint is conducted (see Figure 3-6, Details a, c, and e). The welded shell joint shall be 100% radiographed for a length equal to three times the diameter of the opening, but weld seam being removed need not be radiographed. Radiographic examination shall be in accordance with 6.1.3 through 6.1.8.

Dalam dokumen Welded Steel Tanks for Oil Storage (Halaman 43-47)