API RP 581 - 3rd Ed.2016 - Add.2-2020 - Risk-Based Inspection Methodology

2-38 API RECOMMENDED PRACTICE 581
5.5.2 Inspection Effectiveness
Inspection is ranked according to the effectiveness of the methods and coverage for detecting a specific
damage mechanism. Although inspection effectiveness is not currently used in the calculation of the lining
DF, examples of inspection activities that are both intrusive (requires entry into the equipment) and
nonintrusive (can be performed externally) are provided in Annex 2.C, Table 2.C.6.1.
5.5.3 Calculation of the DF
The following procedure may be used to determine the DF for lining damage; see Figure 5.1.
a) STEP 1—Determine the lining type and time in service, age, of the lining based on the lining installation
date or date of last A or B effectiveness inspection.
b) STEP 2—Determine the base value of the lining DF,
elin
D fB
, using Table 5.4 and Table 5.5, as
applicable, based on the age and lining type from STEP 1.
c) STEP 3—Determine the DF for lining damage,
elin
D f
, using Equation (2.22).
elin elin
Df DfB FLC FOM
= ⋅ ⋅ (2.22)
The adjustment factors are determined as described below.
1) Adjustment for Lining Condition, F LC —The adjustment factors are given in Table 5.6 based on a
qualitative assessment of the lining condition.
2) Adjustment for On-line Monitoring, F OM —Some lined components have monitoring to allow early
detection of a leak or other failure of the lining. The monitoring allows orderly shutdown of the
component before failure occurs. If on-line monitoring is used, and it is known to be effective at
detecting lining deterioration, F OM = 0.1; otherwise F OM = 1.0. Examples of monitoring systems
include thermography or heat sensitive paint (refractory linings), weep holes with detection devices
(loose alloy linings), and electrical resistance detection (glass linings).
5.6 Nomenclature
age
is the time since the last A or B effective lining inspection
elin
D f
is the DF for liners
elin
D fB
is the base value of the DF for liners
F LC
F OM
is the DF adjustment for lining condition
is the DF adjustment for online monitoring