2 Tee or Cross Joint

2.1 Application

2.1.1

The connection of primary supporting members, stiffener webs to plating as well as the plating abutting on another plating, are to be made by fillet or penetration welding, as shown on Figure 1.

Figure 1 Tee or cross joints

t_as-built : As-built thickness of the member being attached, mm.

θ : Connecting angle, in deg.

2.1.2

Where the connection is highly stressed or otherwise considered critical, a partial or full penetration weld is to be achieved by bevelling the edge of the abutting plate.

2.2 Continuous fillet welds

2.2.1

Continuous welding is to be adopted in the following locations: a

Connection of the web to the face plate for all members.
All fillet welds where higher strength steel is used.
Boundaries of weathertight decks and erections, including hatch coamings, companionways and other openings.
Boundaries of tanks and watertight compartments.
All structures inside tanks and cargo holds.
Stiffeners and primary supporting members at tank boundaries.
All structures in the aft peak and stiffeners and primary supporting members of the aft peak bulkhead.
All structures in the fore peak.
Welding in way of all end connections of stiffeners and primary supporting members, including end brackets, lugs, scallops, and at orthogonal connections with other members.
All lap welds in the main hull.
Primary supporting members and stiffener members to bottom shell in the 0.3 L forward region.
Flat bar longitudinals to plating.
The attachment of minor fittings to higher strength steel plating and other connections or attachments.
Pillars to heads and heels.
Hatch coaming stay webs to deck plating, see [2.4.5].

2.3 Intermittent fillet welds

2.3.1

Where continuous welding is not required, intermittent welding may be applied.

2.3.2

Where beams, stiffeners, frames, etc, are intermittently welded and pass through slotted girders, shelves or stringers, there is to be a pair of matched intermittent welds on each side of every intersection. In addition, the beams, stiffeners and frames are to be efficiently attached to the girders, shelves and stringers.

Where intermittent welding or one side continuous welding is permitted, double continuous welds are to be applied for one-tenth of their shear span at each end, in accordance with [2.5.2] and [2.5.3].

2.3.3 Deckhouses

One side continuous fillet welding is acceptable in the dry spaces of deckhouses.

2.3.4 Size for one side continuous weld

The size for one side continuous weld is to be of fillet required by [2.5.2] for intermittent welding, where f₃ factor is to be taken as 2.0.

2.4 Partial or full penetration welds

2.4.1 High stress area definition

For the application of this section, high stress area means an area where fine mesh finite element analysis is to be carried out and the fine mesh yield utilisation factor in elements adjacent to the weld is more than 90% of the fine mesh permissible utilisation factor, as defined in Ch 7, Sec 3, [6.2].

2.4.2 Partial or full penetration welding

In areas with high tensile stresses or areas considered critical, full or partial penetration welds are to be used.

In case of full penetration welding, the root face is to be removed, e.g. by gouging before welding of the back side.

For partial penetration welds the root face, f, is, to be taken between 3 mm and t_as-built /3. The groove angle made to ensure welding bead penetrating up to the root of the groove, α, is usually from 40° to 60°.

The welding bead of the full/partial penetration welds is to cover root of the groove.

Examples of partial penetration welds are given on Figure 2

Figure 2 Partial penetration welds

2.4.3 One side partial penetration weld

For partial penetration welds with one side bevelling the fillet weld at the opposite side of the bevel is to satisfy the requirements given in [2.5.2].

2.4.4 Extent of full or partial penetration welding

The extent of full or partial penetration welding in each particular location listed in [2.4.5] and [2.4.6] is to be approved by the Society. However, the minimum extent of full/partial penetration welding from the reference point (i.e. intersection point of structural members, end of bracket toe, etc.) is not to be taken less than 300 mm, unless otherwise specifically stated.

2.4.5 Locations required for full penetration welding

Full penetration welds are to be used in the following locations and elsewhere as required by the rules, see Figure 3:

Floors to hopper/inner bottom plating in way of radiused hopper knuckle.
Radiused hatch coaming plate at corners to deck.
Connection of vertical corrugated bulkhead to the lower hopper plate and to the inner bottom plate within the cargo hold region, when the vertical corrugated bulkhead is arranged without a lower stool.
Connection of structural elements in the double bottom in line with corrugated bulkhead flanges to the inner bottom plate, when the vertical corrugated bulkhead is arranged without a lower stool.
Connection of vertical corrugated bulkhead to the lower hopper plate, and connection of structural elements in the lower hopper area in line with corrugated bulkhead flanges to the lower hopper plate, where connections are clear of lower stools.
Connection of vertical corrugated bulkhead to top plating of lower stool.
Corrugated bulkhead lower stool side plating to lower stool top plate.
Corrugated bulkhead lower stool side plating to inner bottom.
Connection of structural elements in double bottom to the inner bottom plate in holds intended for the carriage of liquid at sea with a distance of 300 mm from the side plating of the lower stool, see Figure 3.
Edge reinforcement or pipe penetration both to strength deck, sheer strake and bottom plating within 0.6 L amidships, when the dimensions of the opening exceeds 300 mm.
Abutting plate panels with as-built thickness less than or equal to 12 mm, forming outer shell boundaries below the scantling draught, including but not limited to: sea chests, rudder trunks, and portions of transom. For as-built thickness greater than 12 mm, partial penetration in accordance with [2.4.2].
Crane pedestals and associated bracketing and support structure.
For toe connections of longitudinal hatch coaming end bracket to the deck plating, full penetration weld for a distance of 0.15 H_c from toe of side coaming termination bracket is required, where H_c is the hatch coaming height.
Rudder horns and shaft brackets to shell structure.
Thick flanges of long transverse web frames to side web frames. Thick flanges of long longitudinal girder to bulkhead web frames.

2.4.6 Locations required for partial penetration welding

Partial penetration welding as defined in [2.4.2], is to be used in the following locations (see examples in Figure 3).

Connection of hopper sloping plate to longitudinal bulkhead (inner hull).
Longitudinal/transverse bulkhead primary supporting member end connections to the double bottom.
Corrugated bulkhead lower stool supporting floors to inner bottom.
Corrugated bulkhead gusset and shedder plates.
Lower 15% of the length of built-up corrugation of vertical corrugated bulkheads.
Structural elements in double bottom below bulkhead primary supporting members and stool plates, except in way of 2.4.5i)..
Lower hopper plate to inner bottom.
Horizontal stringers on bulkheads in way of their bracket toe and the heel.

Figure 3 : High stress areas welding (examples)

2.4.7 Fine mesh finite element analysis

In high stress area, at least partial penetration welds as defined in [2.4.2] are to be used. The minimum extent of full or partial penetration welding in that case is to be the greater of the following:

150 mm in either direction from the element with the highest yield utilisation factor.
The extent covering all elements that exceed the above mentioned yield utilisation factor criteria.

2.4.8 Shedder plates

In case where shedder plates are fitted at the lower end of corrugated bulkhead, the shedder plates are to be welded to the corrugation and the top plate of the transverse lower stool by one side penetration welds.

2.5 Weld size criteria

2.5.1

The required weld sizes are to be rounded to the nearest half millimetre.

2.5.2

The leg length, ℓ_leg in mm, of continuous, lapped or intermittent fillet welds is not to be taken less than the greater of the following values:

ℓ_leg = f₁ f₂ t_{as – built}

ℓ_leg = f_yd f_weld f₂ f₃ t_{as – built}+ t_gap

ℓ_leg as given in Table 1.

where:

f₁ : Coefficient depending on welding type:

f₁ = 0.30 for double continuous welding.
f₁= 0.38 for intermittent welding.

f₂ : Coefficient depending on the edge preparation:

f₂ = 1.0 for welds without bevelling.
f₂ = 0.70 for welds with one/both side bevelling and f = t_as-built /3.

f_yd : Coefficient not to be taken less than the following:

R_{eH_weld} : Specified minimum yield stress for the weld deposit in N/mm², not to be less than:

:R_{eH_weld} = 305 N/mm² for welding of normal strength steel with R_eH = 235N/mm².
: R_{eH_weld} = 375 N/mm² for welding of higher strength steels with R_eH from 265 to 355 N/mm².
: R_{eH_weld} = 400 N/mm² for welding of higher strength steel with R_eH = 390N/mm².

f_weld : Weld factor dependent on the type of the structural member, see Table 2, Table 3 and Table 4.

k : Material factor of the abutting member.

f₃ : Correction factor for the type of weld:

f₃ = 1.0 for double continuous weld.
f₃ = s_ctr /ℓ_weld for intermittent or chain welding.

s_ctr : Distance between successive fillet welds, in mm.

2.5.3

The throat size t_throat, in mm, as shown in Figure 4, is not to be less than:

Figure 4 : Weld scantlings definitions

Table 1 : Minimum leg size

Area	Type of space		Minimum length, in mm
Cargo hold region	Cargo tanks and holds	Within 3m below top of tank ⁽²⁾	6.5⁽¹⁾
	Cargo tanks and holds	Elsewhere	6.0⁽¹⁾
	Water ballast tanks	Within 3m below top of tank ⁽²⁾	6.5⁽¹⁾
	Water ballast tanks	Elsewhere	6.0⁽¹⁾
	Dry spaces and voids		5.0
	Other tanks		6.0^⁽¹⁾
Other areas	Water ballast tanks	Within 3m below top of-tank ⁽²⁾	6.0⁽¹⁾
	Water ballast tanks	Elsewhere	5.5⁽¹⁾
	Fuel oil, diesel oil, fresh water and other tanks		4.5
	Dry spaces and voids		4.0
	Superstructures and deckhouses		3.5
(1) If the as-built thickness of the element is less than 12 mm, the minimum leg length may be reduced by 0.5 mm. (2) Only applicable to cargo tanks and ballast tanks with weather deck as the tank top. The 3m distance is measured vertically from and parallel to the top of the tank.

Table 2 : Weld factors for different structural members

Hull area	Connection				f_weld
Hull area	Of		To		f_weld
General, unless otherwise specified in the table	Watertight plate		Boundary plating		0.48
	Oil-tight plate		Boundary plating		0.51
	Brackets at ends of members				0.48
	Ordinary stiffener and collar plates		Deep tank bulkheads		0.24
	Ordinary stiffener and collar plates		Web of primary supporting members and collar plates		0.38
	Web of stiffener		Plating (except deep tank bulkhead)		0.20
Bottom and double bottom			Face plates of built-up stiffeners	At ends (15% of span)	0.38
			Face plates of built-up stiffeners	Elsewhere	0.20
	Ordinary stiffener		Bottom and inner bottom plating		0.24
	Centre girder		Shell plates		0.38
	Centre girder		Inner bottom plate		0.38
	Side girder including intercostal plates		Bottom and inner bottom plating		0.24
	Floor		Shell plates and inner bottom plates	At ends, on a length equal to two frame spaces	0.38
			Centre girder and side girders in way of hopper tanks		0.38
			Elsewhere		0.24
	Bracket on centre girder		Centre girder, inner bottom, floors and shell plates		0.38
	Web stiffener		Floor and girder		0.20
Side and inner side in double side structure	Web of primary supporting members		Side plating		0.30
			Inner side plating and web of primary supporting members	in way of deck transverse and end connections	0.43
				in way of cross tie	0.36
				elsewhere	0.30
Deck	Strength deck	t_{as_built} ≥ 13	Side shell plating within 0.6L midship		PPW⁽³⁾
		t_{as_built} ≥ 13	Elsewhere		0.48
		t_{as_built} < 13	Side shell plating		0.48
	Other deck		Side shell plating		0.38
	Other deck		Stiffeners		0.20
	Hatch coamings		Deck plating	Longitudinal hatch coaming at corners of hatchways on a length of 15% of the hatch coaming height	FPW ^{(4) (1)}
				Longitudinal hatch coaming on a length starting from 15% of the hatch coaming height from the corners of hatchways up to 15% of the hatch length	0.48
				Elsewhere	0.38
	Web stiffeners		Coaming webs		0.20 ⁽²⁾
Bulkheads⁽⁵⁾	Non-watertight bulkhead structure		Boundaries	Swash bulkheads	0.24
Bulkheads⁽⁵⁾	Stiffener		Bulkhead plating	At ends (25% of span), where no end brackets are fitted	0.48
Aft peak	Internal members		Boundaries and each other: below waterline		0.38
Aft peak	Internal members		Above waterline		0.20
Fore peak	Internal members		Boundaries and each other		0.20
Machinery space	Centre girder		Keel and inner bottom		0.48
	Floor		Centre girder		0.48
	Engine foundation girders		Top plate and primary hull structure		PPW ⁽³⁾
	Floors and girders		Inner bottom and shell plate		0.38
Super-structure and deckhouse	External bulkhead (first and second tier erections)		Deck, external bulkhead		0.48
Super-structure and deckhouse	External bulkheads and internal bulkheads		Elsewhere		0.20
(1) f_weld =0.43 for hatch coaming other than in cargo holds. (2) Continuous welding. (3) PPW: Partial penetration welding in accordance with [2.4.2]. (4) FPW: Full penetration welding in accordance with [2.4.2]. (5) Bulkheads of superstructure and deckhouse are to be considered in the row corresponding to “Superstructure and deck house”.

Table 3 : Weld factors for miscellaneous fittings and equipment

Item	Connection to	f_weld
Hatch cover	Watertight/oil-tight joints	0.48 ⁽¹⁾
	At ends of stiffeners	0.38 ⁽²⁾
	Elsewhere	0.24
Mast,derrick post, crane pedestal, etc.	Deck/ Underdeck reinforced structure	0.43
Deck machinery seat	Deck	0.24
Mooring equipment seat	Deck	0.43
Ring for access hole type cover	Anywhere	0.43
Stiffening of side shell doors and weathertight doors	Anywhere	0.24
Frames of shell and weathertight doors	Anywhere	0.43
Coaming of ventilator and air pipe	Deck	0.43
Ventilators, etc., fittings	Anywhere	0.24
Ventilators, air pipes, etc., coaming to deck	Deck	0.43
Scupper and discharge	Deck	0.55
Bulwark stay	Deck	0.24
Bulwark plating	Deck	0.43
Guard rail, stanchion	Deck	0.43
Cleats and fittings	Hatch coaming and hatch cover	0.60 ⁽³⁾
(1) For bulk carrier hatch covers, f_weld= 0.38 for watertight joints. (2) For bulk carrier hatch covers, f_weld = 0.24 at ends of stiffeners. (3) Minimum weld factor. Where t_as-built > 11.5mm, ℓ_leg need not exceed 0.62 t_as-built.Penetration welding may be required depending on design.

2.5.4

For primary supporting members connections not listed in Table 2 and Table 3, the weld factors from Table 4 are to be used.

Table 4 : Weld factors for primary supporting members

Hull structural member	Connection			f_weld
	Of	To
Primary supporting member	Web plate	Shell plating, deck plating, inner bottom plating, bulkhead	Within end 15% of shear span and extending to end of member	0.48
			Elsewhere	0.38
		Face plate	In tanks/holds Members located within 0.125L from fore peak	0.38
			Elsewhere if cross section area of face plate exceeds 65 cm²	0.38
			Elsewhere	0.24
	End connections		In way of boundaries of ballast and cargo tanks	0.48
			Elsewhere	0.38

2.5.5

Where the as-built web thickness of the abutting longitudinal stiffener is greater than 15 mm and exceeds the thickness of the attached plating, the welding is to be double continuous and the leg length of the weld is not to be less than the largest of the following:

0.30 t_as-built, where t_as-built is the as-built thickness of the attached plating without being taken greater than 30 mm.
0.27 t_as-built + 1, where t_as-built is the as-built thickness of the abutting member. The leg size resulting of this formula needs not to be taken greater than 8.0 mm.
Leg length given in the Table 1.

2.5.6

Where the minimum weld size is determined by the requirements of second formula shown in [2.5.2], the weld connections to shell, decks or bulkheads are to take account of the material lost in the cut out, where stiffeners pass through the member. In cases where the width of the cut-out exceeds 15 % of the stiffener spacing, the size of weld leg length is to be multiplied by:

where:

s : Stiffener spacing in mm, as shown in Figure 5.

ℓ_w : Length of web plating between notches, in mm, as shown in Figure 5.

Figure 5 : Effective material in web cut-outs for stiffeners

2.5.7 Shear area of primary supporting member end connections

Welding of the end connections, inclusive 10% of shear span, of primary supporting members is to be such that the weld area is to be equivalent to the gross cross sectional area of the member. The weld leg length in mm, ℓ_leg, is to be taken as:

where:

h_w : Web height of primary supporting members, in mm.

t_{gr_req} : Required gross thickness of the web in way of the end connection, including 10% of shear span, based on the highest average usage factor for yield from cargo hold FE analysis or the shear area requirement for PSM outside cargo hold region, in mm.

ℓ_weld : Length of the welded connection in mm, as shown in Figure 6.

ℓ_dep : Total length of deposit of weld metal, in mm, see Figure 6 taken as:

ℓ_dep= 2 ℓ_weld

The size of weld is not to be less than the value calculated in accordance with [2.5.2].

2.5.8 Longitudinals

Welding of longitudinals to plating is to be doubled continuous at the ends of the longitudinals at the extent of 15 % of shear span as defined in Ch 3, Sec 7, [1.1.3].

In way of primary supporting members, the length of the double continuous weld is to be equal to the depth of the longitudinal or the end bracket, whichever is greater.

Figure 6 : Shear area of primary supporting member

Note 1: The length ℓ_weld is the length of the welded connection. The total length of the weld deposit ℓ_dep if welded with double continuous fillet welds is twice the length of the welded connection ℓ_weld.

2.5.9 Deck longitudinals

For deck longitudinals, a matched pair of welds is required at the intersection of longitudinals with primary supporting members.

2.5.10 Longitudinal continuity provided by brackets

Where a longitudinal strength member is to cut at a primary supporting structure and the continuity of strength is provided by brackets, the weld area A_weld is not to be less than the gross cross sectional area of the member. The weld area, A_weld in cm², is to be determined by the following formula:

2.5.11 Unbracketed stiffeners

Where intermittent welding is permitted, unbracketed stiffeners of shell, watertight and oil-tight bulkheads, and deckhouse fronts are to have double continuous welds for one-tenth of their length at each end. Unbracketed stiffeners of non-tight structural bulkheads, deckhouse sides and aft ends are to have a pair of matched intermittent welds at each end.

2.5.12 Reduced weld size

Where an approved automatic deep penetration procedure is used and quality control facilitates are working to a gap between members of 1 mm and less, the weld factors given in Table 2 may be reduced by 15% but not more than fillet weld leg size of 1.5 mm. Reductions of up to 20%, but not more than the fillet weld leg size of 1.5 mm, will be accepted provided that the shipyard is able to consistently meet the following requirements:

The welding is performed to a suitable process selection confirmed by welding procedure tests covering both minimum and maximum root gaps.
The penetration at the root is at least the same amount as the reduction into the members being attached.
Demonstrate that an established quality control system is in place.

2.5.13 Reduced weld size justification

Where any of the methods for reduction of the weld size are adopted, the specific requirements giving justification for the reduction are to be indicated on the drawings. The drawings are to document the weld design and dimensioning requirements for the reduced weld length and the required weld leg length given by [2.5.2] without the leg length reduction. Also, notes are to be added to the drawings to describe the difference in the two leg lengths and the requirements for their application.