Operating Practices

Operating Practices

INTRODUCTION

Section 9 discusses operating practices that should be fol­lowed to provide integrity of equipment and continuity of work practices in operations involving the design and han­dling of materials in hydrogen sulfide service (refer to Par.

and applicable regulatory requirements). Each equipment
installation or work procedure should be reviewed and ob­
served as often as necessary to detect when changes may be
needed in operating practices or equipment. Water injection
and other enhanced recovery operations may result in the in­
troduction of bacteria that can cause water soluble hydrogen
sulfide to develop over time and be present in produced
fluids.

EMERGENCY PROCEDURES

Emergency operating and shutdown procedures shall be posted or readily available to operating personnel.

TEST PROCEDURES

Tests of the gas phase of produced fluids shall be con­ducted periodically to determine the hydrogen sulfide con­centration. Procedures should be established and routine operational tests should be conducted periodically for hydro­gen sulfide detection and monitoring equipment and alarm devices, forced air ventilation systems, and similar safety de­vices. Results of these tests should be recorded.

SAFE WORK PRACTICES

Safe operating procedures should be developed for per­forming operations and maintenance (e.g., tank gauging, wa­ter line blowdown, line repair, valve replacement, and sampling) so hazards due to the release of hydrogen sulfide can be avoided. A safety review of the work should be per­formed prior to beginning any maintenance or operating work activities requiring personnel to be in areas that could contain concentrations of hydrogen sulfide or sulfur dioxide exceeding the levels stipulated in Par. 4.1. Legible warning signs, such as "HYDROGEN SULFIDE OPER­ATIONS—ENTER ONLY WHEN MONITORING SHOWS THE AREA TO BE SAFE" or "RESPIRATORY PROTECTION MUST BE WORN BEYOND THIS POINT", should be prominently posted in the area where produced fluids containing hydrogen sulfide (refer to Par. 4.1 for applicability) are being handled or processed.

Note: Regulatory requirements for sign posting shall be observed.

LEAK DETECTION

In produced fluids handling systems containing hydrogen sulfide in concentrations capable of causing atmosphere con-

centrations in excess of 10 ppm, monitoring techniques or procedures (for example, visual observation, soap bubble test, portable detection equipment, fixed monitoring equip­ment) should be employed to detect leaks. Particular atten­tion should be given to enclosed facilities (refer to Section 12).

SAFE WORK PERMITS

For activities without previously established operating procedures, special safety review documentation (e.g., hot work permits and check-off lists) outlining specific safety precautions with specific authorization should be used. Doc­umentation should include personnel protective equipment required; equipment that should be properly blinded, blanked, or disconnected; equipment and piping that should be properly vented; procedures for excavation of buried lines in processing areas; etc.

VALVES, CONNECTIONS, AND GAUGES

Valves, flanges, gauges, connections, and other compo­nents should be observed for evidence of needed inspection, repair, or maintenance. The cause of equipment failure should be investigated and determined. If failure is caused by exposure to hydrogen sulfide, alternate methods or equip­ment should be considered.

ARTIFICIAL LIFT WELLS

Artificial lift wells should be observed for any change in operating conditions that could cause leaks or failures. Sig­nificant changes in wellhead pressure, gas-oil-water ratios, flow rates, and similar parameters should be evaluated to prevent leaks or failures.

FLOWING WELLS

Annuli of flowing wells should be tested at regular inter­vals for any pressure changes. Such pressure changes may indicate a downhole failure of the packer, tubing, or casing. Changes in fluid volumes or ratios, fluid corrosivencss, and surface pressures should be evaluated to determine the need for corrective measures.

FLOW/GATHERING LINES

Flow line and gathering line right-of-ways should be ob­served for conditions conducive to pipeline failures, such as those caused by excavation, construction, trespassing, or sur­face erosion.

PRESSURE VESSELS

Relief valves and other applicable components on pres­sure vessels shall be tested according to regulatory require­ments or company policy. Refer to API 510 and API

PRESSURE RELIEF AND NORMALLY
VENTING DEVICES

The discharge of pressure relief and normally venting de­vices should be located away from work areas and designed to maximize dispersion and minimize personnel exposure to hydrogen sulfide. Refer to Par. 8.1.4 for considerations for materials applications in hydrogen sulfide service.

STORAGE TANKS

Produced liquids storage tanks should be observed for needed repairs or maintenance. The tank thief hatch seals, in­spection and clean-out plate seals, vent line back-pressure valves, etc., should be serviced or replaced as appropriate. Refer to API Recommended Practice 12R1.

FLARE SYSTEMS

Ignition devices for flare systems handling hydrogen sul­fide in hazardous concentrations should be inspected and serviced regularly to ensure proper operation.

MONITORING EQUIPMENT-
MAINTENANCE, TESTING, AND
CALIBRATION

Monitoring equipment used to detect occupational expo­sure levels of hydrogen sulfide shall be serviced and tested at intervals recommended by the manufacturer, and possibly more frequently under extreme humidity, temperature, dust, or other adverse environmental operating conditions. The monitoring equipment should be calibrated by qualified indi­viduals at intervals frequent enough to enable the user to de­termine an acceptable calibration schedule. The equipment should be calibrated once every three (3) months, at intervals not exceeding 100 days. Refer to ISA Recommended Prac­tice 12.15, the equipment manufacturer's instruction manual, and Section 10.

CORROSION MONITORING

A corrosion monitoring program should be established to detect and mitigate internal and external corrosion activity that can affect equipment in hydrogen sulfide service.

CONFINED SPACE ENTRY

Enclosures with known or potential hydrogen sulfide haz­ards and restricted means of entrance and exit deserve spe­cial attention. These enclosures are not normally occupied by people nor well ventilated. Examples of such enclosures in the oil and gas producing and gas processing plant industries may include tanks, cellars, process vessels, tank trucks, tem­porary and permanent pits and trenches, and barges. A con-

fined space entry permit shall be required for entry into a confined space. A confined space entry permit should as a minimum:

a. identify the job site.

b. indicate the date and duration of the permit.

с specify testing requirements and other conditions to safely perform the job.

d. ensure that sufficient monitoring is conducted to ascertain
that the hydrogen sulfide, oxygen,²² or hydrocarbon concen­
trations do not become a health or fire hazard, and

e. bear the approval specified in the operator's procedure.

As an alternate to foregoing Par. 9.17, Item d, proper per­sonal protective breathing equipment may be worn during the work operation; however, sufficient monitoring of the en­closure atmosphere shall be performed to ensure that it is free of an ignitable mixture of hydrocarbons. Refer to OSHA's Confined Space Entry Standard (29 Code of Fed­eral Regulations Part 1910.146)

ENCLOSED FACILITY ENTRY

Personnel shall use extreme caution before entering en­closed facilities such as buildings housing oil, gas, or pro­duced water processing and handling equipment containing hazardous concentrations of hydrogen sulfide. Personnel shall either establish that entry without personal protective breathing (respiratory protection) apparatus will be safe or shall wear protective breathing equipment. Refer to Section 12 for additional details and precautions.

IRON SULFIDE PRECAUTIONS

Iron sulfide, a reaction product of hydrogen sulfide and iron or spent iron sponge (a treating material), when exposed to air, can autoignite (spontaneous combustion) and burn. Iron sulfide, when exposed to air, should be kept wet until it can be disposed of in accordance with applicable regulations. Iron sulfide scale can accumulate on inside surfaces of ves­sels and on filter elements used in amine systems and be­come an autoignition hazard if exposed to atmospheric oxygen. One of the products of burning iron sulfide is sulfur dioxide; proper safety procedures must be effected to deal with this toxic substance.

DRILLING OPERATIONS

Refer to API Recommended Practice 49 for recommended procedures for drilling and drill stem testing operations in­volving hydrogen sulfide.

SAFETY PRECAUTIONS FOR SAMPLING
AND TANK GAUGING OPERATIONS

When it is known or suspected that the system to be sam­pled or gauged may contain hydrogen sulfide, special pre­cautions shall be observed. Production tanks shall be tested to determine their hydrogen sulfide content (refer to Par. 9.3). Tests should also be conducted within the normal worker breathing zone to determine if the levels stipulated in Par 4.1 may be exceeded and if engineering controls, admin­istrative procedures, or personal protective breathing equip­ment (refer to Par. 6.4) may be required for sampling or tank gauging operations. The tests should be conducted under op­erating and atmospheric conditions to determine the maxi­mum hydrogen sulfide exposure level.

If the hydrogen sulfide level in the worker breathing zone exceeds IDLH level (300 ppm), in addition to appropriate personal protective breathing equipment (refer to Par. 6.4), rescue precautions and procedures (refer to Pars. 6.5 and 6.6) shall be utilized.

FACILITIES ABANDONMENT—SURFACE
EQUIPMENT

Precautions should be taken to ensure that hazardous quantities of hydrogen sulfide do not remain in abandoned surface equipment, including buried pipelines and flow lines. Pipelines and flow lines left in place should be purged, bullplugged, or otherwise capped. Vessels should be flushed with water, purged, drained, and left open to the atmosphere. Precautions should be taken to prevent an iron sulfide fire (refer to Par. 9.19).

CAUTION: Prior to abandonment, vessels should be checked for the presence of naturally occurring radioactive material (NORM) and appropriate safety and handling procedures should be exercised. Refer to API Bulletin E-2 for guidance on management of NORM.

WELL ABANDONMENT

The following recommended practices are not intended to supersede federal, state, or local regulations for well aban­donment. Where not covered by applicable regulations, the practices and well conditions should be considered in plan­ning and effecting permanent well abandonment. It is recom­mended that cement be set across formations that are known to produce or could produce hydrogen sulfide in hazardous concentrations. Refer to API Bulletin E-3 for guidance and procedures for plugging and abandoning wells.

CONTINGENCY PLAN REVISIONS

Operating personnel should be observant for changes that would make reconsiderations and possible revisions advis­able in contingency plan coverage, location(s) of monitoring equipment, and location(s) of lease equipment. Some

changes that should be observed and considered are new res­idences or residential areas, stores, businesses, parks, schools, or roads; changes in well operations; and changes in lease facilities. Refer to Section 7 for suggested procedures for planning and implementing contingency plans and emer­gency procedures.