EXCESSIVE PENETRATION

DEFECT WELD

NON VISUAL

EXCESSIVE PENETRATION

EXCESSIVE PENETRATION

Excess weld metal protruding through the root of a fusion (butt) weld made from one side only.

With pipe welding this type of imperfection may cause effects in the fluid flow that can cause erosion and/or corrosion problems.



Common causes
Penetration becomes excessive when the joint gap is too large, the root faces are too small, the heat input to the joint is too high or a combination of these causes.



Acceptance
The criteria which sets the level of acceptable penetration depends primarily on the application code or specification.

• BS 2971 (Class 2 arc welding) requires that the 'penetration bead shall not exceed 3mm for pipes up to and including 150mm bore or 6mm for pipes over 150mm bore'.
• BS 2633 (Class 1 arc welding) gives specific limits for smaller diameters pipes, eg for pipe size 25-50mm the maximum allowed bore penetration is 2.5mm.
• ASME B31.3 bases acceptability on the nominal thickness of the weld, for instance, allowing for a thickness range of 13-25mm up to 4mm of protrusion. However, ASME notes that 'more stringent criteria may be specified in the engineering design'.
• BS EN ISO 5817 (Quality levels for imperfections), which supersedes BS EN 25817, relates the acceptable protrusion to the width of the under-bead as follows:

Avoidance
It is important to ensure that joint fit-up is as specified in the welding procedure. If welder technique is the problem then re training is required.

ROOT CONCAVITY

DEFECT WELD

NON VISUAL

ROOT CONCAVITY

ROOT CONCAVITY

Because :
1. Gap too wide
2. SPEED ROOT too high .
3. AMPERE ROOT high
4. ELEKTRODA too big.
5. For STAINLESS STEEL ROOT GTAW In override in topped with GTAW So that root melted again and sucked up by the process of caping.


Result
1. Started erosion abrasion.
2. S.C.C ( CL2 , NaOH ).
3. weaken weld join .


Countermeasures :
1. GOUGING until the root , setting again and repair welding as WPS Repair.



Rejected Criteria
API 1104 :
1) IF INDIVIDUAL > ¼ INCI,
2) SEPANJANG TEBAL PIPA ,
3) all length welding 12” > ½ “ .



ANSI B 31.3 : The depth of root concavity acceptable when the number of connection plus welding reinforcement > thick nominal ( T W ) b). in 12” length weld > 3inch

HIGH LOW

DEFECT WELD

(VISUAL) 

HIGH LOW

High Low

Because :
1. Any setting
2. Different thick

Result :
1. Started erosion abrasion.
2. Producing a voltage sliding potential to crack

Countermeasures :
1. The prominent part in an oblique 1 : 3 ( ASME VIII ) 1 ; 2.5 ( ANSI B31.3 )

Rejected Criteria
1 ANSI B31.3 : t ≤ ¼ “ max. 1.5 mm ( 1/16 “ ) EXTERNAL t > ¼ ~ ≤ 13 mm ( ½ “ ) , max. 3 mm ( 1/8” )t > 13 mm ( ½ “ ) ~ ≤ 25 mm ( 1” ) ,max 4 mm ( 5/32 “ ) t > 25 mm ( 1 “ ) , max 5 mm ( 3/16 “ )
INTERNAL = 2 X EXTERNAL exceeds the maximum mentioned above, if no do it, rejected

2. API 1104 :

a). If any side of weld opened >2inch individual.
b). in 12” length weld > 3inch