Knowledge

PFA absorbs 0.2-0.4% moisture in 50% lithium bromide at 120°C with little swelling. In 60% LiBr (lower water activity, higher salt concentration) the moisture absorption is 0.1-0.2 per cent. Lower

A titanium sheath heater supported on PTFE brackets in 25% salt chloride brine at 95°C showing crevice corrosion at the support contact locations. The severity depends on the crevice gap. At a tig

IO4-/IO3- +1.6 V *Strong oxidant Sodium periodate (NaIO4) 10% 60 °C The potential of titanium in open circuit varies from +0.2 V (neutral chloride) to +1.0-1.2 V. This potential is in the transpas

PFA sheath heaters in 20% hydrochloric acid at 85°C are in the nucleate boiling regime. The rough surface (Ra 1.0 microm) provides a bubble nucleation site density of 10,000-50,000 sites/cm 2 , a

The titanium surface catalyzes the breakdown of chlorite at 60°C in 15% sodium chlorite (NaClO 2 ): 4ClO 2 - 3ClO 3 - + Cl - . Surface chloride concentration is 1,000-5,000 ppm as opposed to 0 ppm

Reduction of nitrate ions NO₃⁻ + H₂O + 2e⁻ → NO₂⁻ + 2OH⁻ At 95 °C in 40 % ammonium nitrate under cathodic protection at −0.8 V vs. Ag/AgCl The local pH at the titanium surface increases

Reduction of nitrate ions NO₃⁻ + H₂O + 2e⁻ → NO₂⁻ + 2OH⁻ At 95 °C in 40 % ammonium nitrate under cathodic protection at −0.8 V vs. Ag/AgCl The local pH at the titanium surface increases

PFA-coated titanium heaters in 10% hydrofluoric acid at 60°C depend on the coating for protection of the substrate. If a pinhole develops, HF will diffuse laterally under the coating and attack th

The corrosion rate of Grade 2 titanium in 20% sodium persulfate at 50°C is 0.15-0.30 mm/year. At the same temperature, the corrosion rate in 20% hydrogen peroxide is 0.03-0.08 mm/year. The rate is

Caustic cracking (stress corrosion cracking) of grade 2 titanium is caused by 50% sodium hydroxide at 140°C under 2 bar pressure. 5 years max allowed tensile stress to prevent cracking is 50 MPa.

Creep is a limiting issue in PFA heater tubes at 200°C and 3 MPa hoop stress. PFA unfilled has a creep rate of 1-2% per 1,000 hours at 200°C. PFA with 15% glass fiber filler has a creep rate o

In 5% sulfuric acid (H2SO4) at 80°C titanium is protected by a passive oxide coating. Occasional dry-out, when the liquid level drops below the heater, exposing the hot titanium to air. The quick