viene anche definita uns "saldatura chimica" ottenuta con adesivi a base solvente

http://www.marley.co.nz/pdf/plumbing/RubberRing_and_Solvent_...
Solvent Cement
Marley Solvent Cement is designed for solvent welding PVC pipe joints. IT IS NOT AN
ADHESIVE. It is a blend of three aggressive solvents and sufficient resin to provide a brushing consistency.
When applied to the pipe surface these solvents cause the PVC to soften and swell. When two such surfaces are placed in close contact (as in a spigot and socket joint) the softened surfaces mix and on hardening produce a chemically welded joint. Oil, grease, water, or dust on the PVC surface prevents the softening; dust or similar material prevents the intimate contact between the surfaces, thus preventing the making of a full strength joint.
Solvent, which has thickened in the can through evaporation of the solvents, should not be used, as it will not soften the pipe surface sufficiently.
The solvents attack the natural oils in human skin eventually causing serious dermatitis.


http://www.pipa.com.au/PDFs/PVC002.pdf
SOLVENT CEMENT JOINTING OF PVC-U PIPE
Solvent Cement jointing forms a key element of many PVC-U pipe systems, particularly in plumbing applications and smaller diameter infrastructure pipe systems. Achieving a successful joint requires skill and correct products. In these guidelines there is a comprehensive series of instructions detailing how to successfully make a solvent cement joint. Prior to those instructions there is an explanation of the correct products and materials that must be used in this process.
Solvent cement jointing is a “chemical welding” process – not a gluing process. The priming fluid cleans, degreases and softens the surfaces so that the solvent cement bonds the PVC. The solvent cement softens, swells and dissolves the spigot and
socket surfaces, that bond into one solid material as they cure.
Solvent Cements and Joint Type
Whilst PVC-U is by far the most common plastics pipe material that is routinely joined using the solvent cement process it is not the only plastics pipe material to take advantage of this technique. ABS and PVC-C also use solvent cement as a jointing
technique. Typically these pipe systems are found in specialised industrial applications. It is important to only use the solvent cement and primer applicable to the pipe material you are joining. Seek the advice of the supplier when joining these materials.

http://www.henkel.it/italiano/adesivi/all_pdf/pdf_sch_tech/t...

DESCRIZIONE DEL PRODOTTO
Adesivo speciale a base solvente per PVC-U rigido; Tangit PVC-U effettua una saldatura dei supporti sui quali viene applicato.
CAMPI DI IMPIEGO
Tangit è un adesivo a presa rapida specifico per giunzioni longitudinali di tubi in PVC rigido. E’ indicato in modo particolare per l’assemblaggio di tubi e raccordi anche sotto pressione (acqua potabile, gas), grondaie, condutture in PVC rigido per cavi.
Incolla anche ABS e altre materie plastiche sebbene con resistenze inferiori.
La pulizia da grassi e distaccanti sulle parti da incollare si

Le saldature eseguite con Tangit sono resistenti all’acqua. La resistenza chimica, specialmente agli acidi inorganici, dipende dalla resistenza dei tubi, dai tempi di attesa, dal rispetto della tolleranza, dal carico di pressione, dalle temperature di esercizio, dal tipo di acido e dalla sua concentrazione. La durata delle saldature effettuate con Tangit equivale a quella dei tubi in PVC-U.