HON Leak Report – LDARtools

What this report does

Calculates the HON (Hazardous Organic NESHAP, 40 CFR Part 63 Subpart H) valve leak rate for each unit in the selected scope. The output is one aggregate row per unit — not a list of individual leaks — showing the component counts and leak counts that feed into the leak rate formula used to determine whether a unit or facility is eligible for a monitoring skip period.

This report covers valves only. Other component types are filtered out regardless of what is selected. This report is in the Leak folder on the Reports tab.

When to use it

Calculating the current HON leak rate before submitting a skip period request.
Verifying leak rate compliance at the end of a monitoring period.
Tracking how the numerator components (leaks found, excess DORs, leaks repaired via D90) contribute to the rate across different units.

Parameters

Parameter	Description	Required	How it filters
Regulation	The HON regulation to report on	Yes	Only components mapped to this regulation are included
Unit Type	Whether to filter by Process Unit or Location Unit	Yes	Determines which Unit list populates
Units	One or more units to include	Yes	One output row per selected unit
Apply 0.67 Net Deactivated Credit	Whether to apply the 0.67 deactivation credit to the denominator	Yes	Yes multiplies Net Deactivated by 0.67; No uses Net Deactivated count directly
Start Date	Beginning of the monitoring period	Yes	Truncated to the first day of the month containing this date
End Date	End of the monitoring period	Yes	Extended to the last day of the month containing this date

⚠ Date truncation — always use month boundaries. The report operates on full calendar months and silently expands your date range if you enter mid-month dates. A Start Date of March 15 becomes March 1; an End Date of March 15 becomes March 31. If you intend a January–June period but enter January 5 – June 20, you will get January 1 – June 30 — a wider window than intended. Always enter the first day of the first month and the last day of the last month to ensure your period matches your skip-period calculation.

Columns

Column	What it shows	Format / Notes
Unit	Unit name	Text
Monitored	Number of distinct valves that had at least one non-Cooling Tower inspection during the period	Integer
Activated	Number of valves added or reactivated during the period	Integer
DeAct	Number of valves deactivated during the period	Integer
Net Deactivated	Deactivated minus Activated, floored at zero	Integer; net activations are not credited — only net deactivations increase this value
Times 0.67	Net Deactivated multiplied by 0.67, used in the denominator when the deactivation credit is applied	Decimal; shows N/A when the 0.67 credit is not applied
Denominator	Monitored valves plus the deactivation adjustment: Net Deactivated × 0.67 when the credit is applied, or Net Deactivated when it is not	Integer
Leaks Found	Distinct valves that had an inspection and a leak opened during the period	Integer
Pre-Existing DORs	Distinct valves on a DOR that was approved before the period start and was either still open or closed during the period	Integer
Total Valves	Total distinct valves in the selected scope	Integer
1% of Total	Total Valves × 1%, rounded to the nearest whole number — the allowable pre-existing DOR threshold	Integer
Excess DORs	Pre-Existing DORs above the 1% allowance, floored at zero	Integer
Repaired Leaks on D90 Inspections	Distinct valves with a leak opened in the period, found by a D90 inspection, that were repaired and closed	Integer
Numerator	Leaks Found plus Excess DORs, minus Repaired Leaks on D90 Inspections	Integer
Leak Rate	Numerator divided by Denominator, expressed as a percentage rounded to one decimal place	Decimal (%)

What's included and excluded

Included:

Valves only. No other component types are counted in any column, regardless of what component types exist in the selected units.
Only components mapped to the selected regulation.
Only components in the selected unit(s).
Profile history is evaluated across the full period to determine activated and deactivated counts.

Excluded:

All non-valve component types.
Cooling Tower inspections are excluded from the Monitored and Leaks Found counts.

How key values are calculated

Activated

A valve is counted as activated if its profile history shows a transition to Active status during the period, or if the component was added during the period.

DeAct

A valve is counted as deactivated if its profile history shows a transition to Deactivated status during the period.

Net Deactivated

Deactivated minus Activated, floored at zero. If more valves were activated than deactivated during the period, Net Deactivated is zero — net activations are not credited.

Denominator

Monitored valves plus the deactivation adjustment. When the 0.67 credit is applied, the adjustment is Net Deactivated multiplied by 0.67, making the denominator slightly larger and lowering the leak rate. When the credit is not applied, Net Deactivated is added directly. This reflects the HON provision that reduces monitoring requirements for net deactivations.

Repaired Leaks on D90 Inspections

D90 is a Delayed Monitoring inspection reason. Some regulations require that after a leak is closed, the component must receive a follow-up inspection to confirm the repair held — within 90 days (D90) or 30 days (D30). When a technician performs this follow-up inspection, it is recorded with an inspection reason of "D90" (or "D30"). The HON Leak Report uses the D90 reason specifically.

This column counts valves that had a leak opened during the period by an inspection with reason "D90" and that were repaired and closed. These are subtracted from the numerator because the HON regulation allows them to be excluded from the leak count.

Excess DORs

Pre-existing DORs (approved before the period start and either still open or closed during the period), in excess of 1% of total valves. Pre-existing DORs within the 1% allowance are not added to the numerator; only the excess above 1% counts.

Leak Rate

Numerator divided by Denominator, expressed as a percentage rounded to one decimal place (e.g., 2.0 = 2%).

Under 40 CFR Part 63 §63.168, a facility must achieve a valve leak rate at or below 2% to be eligible for a monitoring skip period. This threshold applies to the valve population — run the HON Leak — Pumps and HON Leak — Connectors reports separately to evaluate those component populations.

Tips and common questions

"I entered a mid-month date and the results look wrong." The report silently expands your date range to full calendar months — see the date truncation warning under Parameters. Always use the first day of the first month and the last day of the last month.
"What does 'Apply 0.67 Net Deactivated Credit' mean?" Under HON, when the net count of valves decreases due to deactivations, you can add 0.67 × the net reduction to the denominator. This makes the denominator larger, lowering the calculated leak rate. Select Yes if your facility is taking this credit; No to see the rate without it.
"Why does the Leak Rate appear very high or very low for a small unit?" Small valve counts magnify any single leak or DOR. One leak out of 10 monitored valves = 10% leak rate. This is expected behavior — the HON formula is designed for aggregate assessment across larger populations.
"Repaired Leaks on D90 Inspections is zero even though we had D90 inspections." The count only includes leaks that meet all three conditions: opened during the period, found by a D90 inspection reason, and closed. An open D90 leak or a leak closed before the period start will not be counted.
"The report only shows valves — where are pumps and connectors?" HON Leak Report covers valves only. HON Leak — Pumps and HON Leak — Connectors are separate reports with different parameters and formulas.
"What is a D90 repair?" Under HON (Hazardous Organic NESHAP), certain leaks may qualify for a 90-day repair extension (D90) instead of the standard 15-day repair deadline. A leak repaired under the D90 provision is treated differently in the Leak% calculation — it is subtracted from the numerator rather than counted as an unrepaired leak. Check the applicable regulation subpart for the conditions under which D90 applies.
"What does 'skip-period eligibility' mean?" Under §63.168 of HON, a unit may qualify to skip a monitoring period if its rolling Leak% falls at or below 0.5% for valves over the qualifying window. The HON Leak Report's rolling Leak% is the key metric used to determine whether a unit meets this threshold. If Leak% drops to 0.5% or below, consult your regulation documentation or Chateau administrator to initiate the skip-period process.

Sample output

What the rows illustrate:

ALKY — 24 activations, 0 deactivations; Net Deactivated = 0. Times 0.67 = 0.0 (Credit Applied: Yes, but no net deactivations to credit). Denominator = 814.0. 1 leak found; 3 pre-existing DORs against a 1% allowance of 8 valves, so Excess DORs = 0. Numerator = 1; rate = 0.1%.
CRUDE — 27 activations, 2 deactivations; Net Deactivated = 0 (activations exceed deactivations, floored at zero). 6 leaks found; 0 pre-existing DORs. Numerator = 6; rate = 0.4%.
TANK FARM — The only unit with Net Deactivated > 0: 42 deactivations and 0 activations. With Credit Applied = Yes, Times 0.67 = 28.1 (42 × 0.67), added to the 110 monitored valves to give Denominator = 138.1. 0 leaks found; rate = 0.0%. This row illustrates how the 0.67 credit expands the denominator when net deactivations are present.
CRUDE B — 3 deactivations, 0 activations; Net Deactivated = 3, Times 0.67 = 2.0, Denominator = 708.0 (706 + 2.0). 1 leak found, 1 pre-existing DOR within the 7-valve 1% allowance; Excess DORs = 0. Numerator = 1; rate = 0.1%.
LIGHT POLYMERS — 12 activations, 2 deactivations; Net Deactivated = 0. 1 leak found; 0 pre-existing DORs. Numerator = 1; rate = 0.1%.
TRUCK RACK — Largest monitored population (2044 valves) and highest leak count (13). 31 activations and 31 deactivations net to zero. 6 pre-existing DORs against a 21-valve 1% allowance; Excess DORs = 0. Numerator = 13; rate = 0.6%. All units in this sample fall well below the 2% HON threshold.

Related reports

HON Leak — Pumps — the HON leak rate formula applied to pumps; required alongside this report when evaluating skip-period eligibility for the full equipment population.
HON Leak — Connectors — the HON leak rate formula applied to connectors; same purpose as HON Leak — Pumps for the connector population.
Leak Rate — general-purpose leak rate for any single regulation and inspection type; use when you need a leak rate for M21 or AVO monitoring across all component types.
Simplified Leak History — shows individual leak records rather than an aggregate rate; use to look up the specific leaks that contributed to the HON count.

Output format

One row per unit. Suitable for on-screen viewing, PDF, and Excel export. The report is compact enough to read in the viewer without export.