For piping assemblies, screwed fittings cannot be used for: (a) galvanised piping as corrosion may develop around the threaded section (b) high flow applications as turbulence may be initiated at the threaded section (c) sections that have to be dismantled for maintenance (d) low pressure applications as the depth of the pipe thread reduces the pressure rating of the pipe.

They can measure  the amount of energy gained or lost

Ithink the answer is d

Answerthe half-reaction having the greatest tendency to occur at the anode:     i₂(aq) + 2e⁻  ⇄ 2i⁻  ;   e = +0.53 v======oxidation occurs at the anode. we must therefore find the half-reaction with the greatest tendency to oxidize.the given values of e are reduction potentials (the form of the half-reactions are of reduction).the lower the reduction potential, the higher the potential to oxidize. the half-cell with the lowest reduction potential will have the greatest tendency to oxidize at the anode.the half-reaction having the greatest tendency must be    i₂(aq) + 2e⁻  ⇄ 2i⁻    e = +0.53 vbecause its reduction potential is the lowest out of the three.