Incomplete penetration

Incomplete penetration 100% radiography None permitted None permitted NA None permitted... 

General description. Incomplete penetration describes the condition in which the weld fails to reach the bottom of the weld joint, resulting in a notch located at the root of the weld (Fig. 15.12). This critical defect can substantially reduce the intrinsic mechanical strength of the joint and can combine with environmental factors to produce corrosion fatigue (Chap. 10), stress-corrosion cracking (Chap. 9), or crevice corrosion (Chap. 2). 

Location. Incomplete penetration can occur at any welded joint. 

Identification. If the notch left by incomplete penetration emerges at a visually accessible surface, visual examination, perhaps aided by magnetic-particle or liquid-penetrant techniques, may reveal the defect. Otherwise, ultrasonics, radiography, or eddy-current techniques may have to be used. 

In the last case, this may be a physical problem resulting from incomplete penetration by the extraction solvent into the matrix. Alternatively, incomplete recovery of the analyte may result from chemical binding between the analyte and a constituent of the matrix. This is particularly important in the determination of drugs in body tissues where binding to proteins is known to occur. Problems of this kind are documented in the literature. If a new procedure is being developed, it is necessary to investigate the extraction step, e.g. by using radioactive tracers. 

B Lack of fusion and incomplete penetration None of weld deposit or weld deposit to BM... 

Autosomal dominant diseases are more likely to show late onset of symptoms. The genes involved often encode noncatalytic proteins, and may occasionally show incomplete penetrance or variable expression in a pedigree. 

The unaffected male in generation II has an affected lather, sister, and two sons. He is therefore an obligate carrier in whom the mutation has incomplete penetrance. 

Figure IM-12. Incomplete Penetrance for an Autosomal Dominant Disease...

Other examples of incomplete penetrance include familial breast cancer and retinoblastoma (see Chapter 5). 

Incomplete penetrance (individuals with the disease genotype don t have the disease pherto-type)... 

Variable expression (choice B) refers to differences in the severity of a disorder but does not refer to the complete absence of the disorder, which is incomplete penetrance. 

Figure 13-4. Pedigrees illustrating inheritance of (A) a mitochondrial disorder and (B) an autosomal dominant disorder exhibiting anticipation. In pedigree A note the similarity to the X-linked dominant inheritance pattern (Figure 13-3A), but incomplete penetrance as exemplified by individuals 11-4 and 111-4. In pedigree B, the age of onset, indicated next to the symbols for affected individuals, becomes progressively earlier with each generation.

C Depth of lack of fusion and incomplete penetration Cumulative length of lack of fusion and incomplete penetration [Note (7)] <0.2T <38 mm (1.5 in) in any 150 mm (6 in) weld length ... 

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